Atrioventricular valve replacement

ABSTRACT

Apparatus and methods are described including rotating at least a portion of a valve frame in a first direction and subsequently rotating the valve frame in a second direction. The valve frame includes chord-recruiting arms. An outer surface of each of the chord-recruiting arms has a smooth, convex curvature that extends along substantially a full length of the chord-recruiting arm, such that during the rotation of the portion of the valve frame in the first direction, the chords slide over the outer surface of the chord-recruiting arm without be recruited or caught by the chord-recruiting arm. An inner surface of each of the chord-recruiting arms has a concave curvature, such that during the rotation of the portion of the valve frame in the second direction, the chords are recruited within a space defined by the concave curvature.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. spplication Ser. No.17/263,776 to Again filed Jan. 27, 2021, which is a U.S. national phaseapplication of PCT Application No. PCT/IL/2020/057636 to Agian(published as WO 21/028867), filed Aug. 13, 2020, which claims priorityfrom U.S. Provisional Patent Application 62/886,366 to Agian, filed Aug.14, 2019, entitled “Atrioventricular valve replacement,” which isincorporated herein by reference.

FIELD OF EMBODIMENTS OF THE INVENTION

The present invention relates to medical apparatus and methods, andspecifically to apparatus and methods for implanting a prosthetic valveat an atrioventricular valve.

BACKGROUND

The human heart is a muscular organ that pumps deoxygenated bloodthrough the lungs to oxygenate the blood and pumps oxygenated blood tothe rest of the body by contractions of four chambers.

After having circulated in the body, deoxygenated blood from the bodyenters the right atrium through the vena cava. In a healthy subject, theright atrium contracts, pumping the blood through the tricuspid valveinto the right ventricle. The right ventricle contracts, pumping theblood through the pulmonary semi-lunar valve into the pulmonary arterywhich splits to two branches, one for each lung. The blood is oxygenatedwhile passing through the lungs, and reenters the heart via the leftatrium. The left atrium contracts, pumping the oxygenated blood throughthe mitral valve into the left ventricle. The left ventricle contracts,pumping the oxygenated blood through the aortic valve into the aorta tobe distributed to the rest of the body. The tricuspid valve closesduring right ventricle contraction, so that backflow of blood into theright atrium is prevented. Similarly, the mitral valve closes duringleft ventricle contraction, so that backflow of blood into the leftatrium is prevented. The mitral valve and the tricuspid valve are knownas atrioventricular valves, each of these valves controlling the flow ofblood between an atrium and a ventricle.

In the mitral valve, the mitral annulus defines a mitral valve orifice.An anterior leaflet and a posterior leaflet extend from the mitralannulus. The leaflets are connected by chords to papillary muscleswithin the left ventricle.

During ventricular diastole, in a healthy subject, the left atriumcontracts to pump blood into the left ventricle through the mitral valveorifice. The blood flows through the orifice, pushing the leaflets apartand into the left ventricle with little resistance. In a healthysubject, the leaflets of the aortic valve are kept closed by bloodpressure in the aorta.

During ventricular systole, the left ventricle contracts to pump bloodinto the aorta through the aortic valve, the leaflets of which arepushed open by the blood flow. In a healthy subject, the mitral annuluscontracts, pushing the leaflets inwards and reducing the area of themitral valve orifice by about 20% to 30%. The leaflets coapt toaccommodate the excess leaflet surface area, producing a coaptationsurface that constitutes a seal. The pressure of blood in the leftventricle pushes against the ventricular surfaces of the leaflets,tightly pressing the leaflets together at the coaptation surface so thata tight, leak-proof seal is formed.

An effective seal of the mitral valve during ventricular systole dependson a sufficient degree of coaptation. Improper coaptation may be causedby any number of physical anomalies that allow leaflet prolapse (forexample, elongated or ruptured chords, or weak papillary muscles) orprevent coaptation (for example, short chords, or small leaflets). Thereare also pathologies that lead to a mitral valve insufficiency,including collagen vascular disease, ischemic mitral regurgitation(resulting, for example, from myocardial infarction, chronic heartfailure, or failed/unsuccessful surgical or catheter revascularization),myxomatous degeneration of the leaflets, and rheumatic heart disease.Mitral valve regurgitation leads to many complications includingarrhythmia, atrial fibrillation, cardiac palpitations, chest pain,congestive heart failure, fainting, fatigue, low cardiac output,orthopnea, paroxysmal nocturnal dyspnea, pulmonary edema, shortness ofbreath, and sudden death.

The tricuspid valve includes three leaflets: the septal leaflet, theanterior leaflet, and the posterior leaflet. Each of the valve leafletsis attached to the tricuspid valve annulus, which defines the tricuspidvalve orifice. The leaflets are connected to papillary muscles withinthe right ventricle, by chords. In a healthy subject the tricuspid valvecontrols the direction of blood flow from the right atrium to the rightventricular, in a similar manner to the control of the mitral valve overthe direction of blood flow on the left side of the heart. Duringventricular diastole, the tricuspid valve opens, such as to allow theflow of blood from the right atrium to the right ventricle, and duringventricular systole the leaflets of the tricuspid valve coapt, such asto prevent the backflow of blood from the right ventricle to the rightatrium.

Tricuspid valve regurgitation occurs when the tricuspid valve fails toclose properly. This can cause blood to flow back up into the rightatrium when the right ventricle contracts. Tricuspid valve regurgitationis most commonly caused by right ventricle dilation, which leads to thetricuspid valve annulus dilating, resulting in the valve leafletsfailing to coapt properly.

SUMMARY OF EMBODIMENTS

For some applications of the present invention, a valve frame isprovided for use with a prosthetic valve that is configured to bedeployed within a native atrio-ventricular valve (e.g., the mitralvalve, or the tricuspid valve). The valve frame typically includes avalve frame body that includes a cylindrical part, as well as an atrialpart. Typically, the cylindrical part is configured to support aprosthetic valve within the native atrio-ventricular valve. For example,leaflets of the prosthetic valve may be sutured to the cylindrical part,and/or may be otherwise coupled to the cylindrical part. Typically, theatrial part is configured to be deployed at least partially within thesubject's atrium. Further typically, the cylindrical part is configuredto be deployed at least partially within the subject's ventricle.

For some applications, the atrial part includes a disc-shaped portion(also referred to herein as a flange) and a frustoconical portion.Typically, the disc-shaped portion of the atrial part is configured toseal the valve frame with respect to tissue on the atrial side of thenative atrio-ventricular annulus, and is further configured to preventmigration of the valve frame into the ventricle. The frustoconicalportion typically extends from the disc-shaped portion of the atrialpart to the outer surface of the cylindrical part. For someapplications, the inclusion of the frustoconical portion between thedisc-shaped portion and the cylindrical part (as opposed to directlycoupling the disc-shaped portion to the cylindrical part) reduces alikelihood of regurgitation around the outside of the cylindrical part.

For some applications, a plurality of chord-recruiting arms (e.g., morethan two and/or fewer than twelve arms) extend from a portion of thevalve-frame body that is configured to be placed within the subject'sventricle. For example, four chord-recruiting arms or sixchord-recruiting arms may extend from the valve-frame body. For someapplications, a single chord-fecruiting arm extends from a portion ofvalve-frame body that is configured to be placed within the subject'sventricle. Typically, the chord-recruiting arms extend from thecylindrical part of valve-frame body. Further typically, thechord-recruiting arms extend from a ventricular end of the cylindricalpart (i.e., the end of the valve frame body that is configured to beplaced within the ventricle). Typically, the arms extend radially fromthe valve-frame body, in addition to extending axially from theventricular end of the valve-frame body toward an atrial end of thevalve-frame body (i.e., the end of the valve frame body that isconfigured to be placed within the atrium). Further typically, the armscurve around outside of the valve-frame body in a given circumferentialdirection of curvature.

It is noted that descriptions herein of the arms extending from thevalve-frame body in a given direction should not be interpreted asexcluding additional directions in which the arms are oriented. Rather,the arms being described (or claimed) as extending radially from thevalve-frame body should be interpreted as meaning that the orientationof the arms with respect to the valve-frame body includes a radialcomponent. It is typically the case that, in addition to extendingradially from the valve-frame body, the arms curve circumferentially,and in some cases the orientation of the arms includes an axialcomponent. For some applications, at least along a portion of the arms,and at least in certain configurations of the arms, the arms aredisposed tangentially with respect to the valve-frame body.

Typically, the valve frame, with prosthetic valve leaflets disposedtherein, is delivered to the native atrio-ventricular valve, via adelivery device (e.g., a delivery catheter), and the delivery device isconfigured to maintain the valve frame and the prosthetic valve inradially-constrained configurations (i.e., “crimped” configurations)during the delivery. In accordance with respective applications, thevalve frame is delivered transapically (i.e., via the apex of the leftventricle), transseptally (i.e., via the vena cava, the right atrium,and the interatrial septum), and/or via a different delivery path. Forsome applications, when a distal end of the delivery device is disposedwithin the subject's ventricle, the chord-recruiting arms are deployedamong chords of the native atrio-ventricular valve.

Typically, the chord-recruiting arms are deployed among chords of thenative atrio-ventricular valve by releasing the chord-recruiting armsfrom the delivery device, the chord-recruiting arms being shape set toextend from the valve-frame body, upon being released from the deliverydevice. For some applications, additional techniques are used in orderto cause the chord-recruiting arms to become deployed among chords ofthe native atrio-ventricular valve by releasing the chord-recruitingarms from the delivery device. For example, the valve frame may includelever elements, which are configured to cause the chord-recruiting armsto extend radially. Alternatively or additionally, the arms are coupledto the cylindrical part of the valve frame via stitches, the stitchesacting as hinges, such that the arms pivot about the stitches withrespect to the cylindrical part, as described hereinbelow. Typically,the chord-recruiting arms are released from the delivery device whilethe valve-frame body is still maintained in an at least partiallyradially-constrained configuration by the delivery device. Furthertypically, in this configuration of the valve-frame body (i.e., with thechord-recruiting arms having been released from the delivery device, butwith the valve-frame body still maintained in an at least partiallyradially-constrained configuration by the delivery device), thechord-recruiting arms assume a configuration that is described herein asthe “rotation configuration” of the chord-recruiting arms.

Subsequent to the chord-recruiting arms being deployed among chords ofthe native atrio-ventricular valve (and typically while the valve-framebody is still maintained in the at least partially radially-constrainedconfiguration by the delivery device), at least a portion of the valveframe is rotated, such as to cause the chord-recruiting arms to (a) pullthe native atrio-ventricular valve radially inward toward the valveframe, and (b) twist the native atrio-ventricular valve around the valveframe, by recruiting and deflecting at least a portion of the chords.

Typically, the chord-recruiting arms are configured to curve in a givencircumferential direction with respect to the longitudinal axis of thevalve frame, both when the arms are deployed among the chords (i.e.,when the arms are disposed in their rotation configuration), and whenthe valve-frame body is allowed to radially expand (i.e., when the valveframe assumes its non-radially constrained configuration), as describedin further detail hereinbelow. For example, the arms may curve in aclockwise direction or in a counter-clockwise direction with respect tothe longitudinal axis of the valve frame. Typically, subsequent to thechord-recruiting arms being deployed among chords of the nativeatrio-ventricular valve (and typically while the valve-frame body isstill maintained in the at least partially radially-constrainedconfiguration by the delivery device), the valve frame is rotated in thesame circumferential direction as the direction of the circumferentialcurvature of the arms. For some applications, prior to rotating thevalve frame in this direction, the valve frame is rotated in theopposite circumferential direction. For example, if the arms curve inthe clockwise circumferential direction, then, subsequent to the armsbeing deployed among the chords, the valve frame may first be rotated inthe counterclockwise direction and may subsequently be rotated in theclockwise direction. For some applications, rotating the valve frame inthis manner facilitates recruitment of a greater portion of the chordsthan if the valve frame were to only be rotated in the direction of thecircumferential curvature of the arms.

As described in the above paragraph, for some applications, prior torotating the valve frame in the same circumferential direction as thedirection of the circumferential curvature of the arms, the valve frameis rotated in the opposite circumferential direction. For someapplications, the delivery device is configured such as to perform theinitial rotation of the valve frame through a given angle in theopposite circumferential direction from the direction of thecircumferential curvature of the arms, and to subsequently rotate thevalve frame though a predetermined angle in the direction of thecircumferential curvature of the arms. For some applications, in therotation configuration of the chord-recruiting arms, the outer surfacesof each of the arms has a smooth, convex curvature that extends alongsubstantially the full length of the arm, such that during the initialrotation (against the direction of circumferential curvature of the arm)the chords slide over the outer surfaces of the arm without be recruitedor caught by the arm, and without being damaged by the arms in any way.For some applications, by virtue of the arms being shaped in thismanner, the initial rotation of the valve frame causes a relativelylarge number of chords to be positioned such as to be recruited by eachof the arms in the subsequent rotation step. During the subsequentrotation of the valve frame (in the direction of the circumferentialcurvature of the arms), the chords are recruited and deflected (e.g.,deflected inwardly) by the arms. Typically, in the rotationconfiguration of the chord-recruiting arms, the inner surface of the armhas a concave curvature and the chords are recruited within the spacedefined by the concave curvature, during the subsequent rotation by thevalve frame.

For some applications, a plurality of struts protrude from the outsideof the cylindrical part of the valve frame. Typically, the atrial partis coupled to the cylindrical part by the atrial part being coupled tothe protruding struts, e.g., via stitching or welding. It is noted that,typically, during the crimping of the valve frame, there is a lot ofstrain that is placed on the junctions from which the protruding strutsprotrude from the cylindrical part, since the struts pivot about thesejunctions. If the atrial part were to be directly coupled to thecylindrical part at these junctions, then this would mean that thesepoints at which there is relatively large strain placed on the valveframe are also points at which the two pieces are coupled to each other,which would make the frame susceptible to fatigue at these points. Bycontrast, by virtue of the cylindrical part including protruding strutsand the atrial part being coupled to the cylindrical part via thestruts, there is a separation between the points of high strain and thepoints at which atrial part is coupled to the cylindrical part.

It is further noted that, typically, the protruding struts protrude froman axial location along the cylindrical part that is in the lowest 90percent (e.g., the lowest 70 percent, or the lowest 50 percent) of theheight of the cylindrical part. Typically, the cylindrical part has aheight of at least 15 mm, in order to accommodate the coupling of thevalve leaflets to the cylindrical part. If the protruding struts were toprotrude from the top of the cylindrical part (or if the atrial partwere to be coupled directly to the cylindrical part at the top of thecylindrical part), then the entire height of the cylindrical part wouldbe disposed below the atrial part. By contrast, since the protrudingstruts protrude from the lowest 90 percent (e.g., the lowest 70 percent,or the lowest 50 percent) of the height of the cylindrical part, thereis typically axial overlap between the atrial part and the cylindricalpart of the valve frame, along the height of the cylindrical part.Typically, this results in a smaller portion of the height of thecylindrical part protruding into the subject's ventricle, then if therewere to be no axial overlap between the atrial part and the cylindricalpart of the valve frame. In turn (when the valve frame is configured forplacement within the subject's left ventricle), this typically reducesobstruction of the left ventricular outflow tract, relative to if alarger portion of the height of the cylindrical part were to protrudeinto the subject's ventricle. In this context, it is noted that, asdescribed hereinabove, chord-recruiting arms are typically configured to(a) pull the native atrio-ventricular valve radially inward toward thevalve frame, and (b) twist the native atrio-ventricular valve around thevalve frame, by recruiting and deflecting at least a portion of thechords of the native atrioventricular valve. Typically, the recruitmentand deflection of the chords in this manner serves to preventobstruction of the left ventricular outflow tract by portions of thenative mitral valve apparatus.

There is therefore provided, in accordance with some applications of thepresent invention, apparatus for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the apparatusincluding:

-   -   a valve frame configured to support the prosthetic valve within        the native atrio-ventricular valve, the valve frame including:        -   an atrial part including a disc-shaped portion configured to            be deployed on an atrial side of the valve annulus;        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the ventricle;        -   a plurality of chord-recruiting arms configured to extend at            least radially from the ventricular end of the cylindrical            part, the chord-recruiting arms being coupled to the            ventricular end of the cylindrical part via stitches, and            the stitches being configured to act as hinges, such that            upon the chord-recruiting arms being released from a            radially-constrained configuration, while the cylindrical            part is held in an at least partially radially-constrained            configuration, the chord-recruiting arms are configured to            extend radially outwardly by pivoting about the stitches            with respect to the cylindrical part.

In some applications, the atrial part further includes a frustoconicalportion, and the frustoconical portion of the atrial part is coupled tothe cylindrical part, such that there is axial overlap between at leastthe frustoconical portion of the atrial part and the cylindrical part.

In some applications, the atrial part further includes a frustoconicalportion, the valve frame further includes a plurality of protrudingstruts that are configured to protrude from outside the cylindricalpart, and the frustoconical portion of the atrial part is coupled to thecylindrical part via the protruding struts.

In some applications, the apparatus further includes a delivery deviceconfigured to:

-   -   deliver the valve frame to the native atrio-ventricular valve,

subsequently, deploy the plurality of chord-recruiting arms among thechords of the nat1ive atrio-ventricular valve, and

-   -   subsequently, rotate at least a portion of the valve frame, such        as to cause the plurality of chord-recruiting arms to (a) pull        the native atrio-ventricular valve radially inward toward the        valve frame, and (b) twist the native atrio-ventricular valve        around the valve frame, by recruiting and deflecting at least a        portion of the chords.

In some applications:

-   -   the delivery device is configured to deploy the plurality of        chord-recruiting arms among the chords of the native        atrio-ventricular valve while maintaining the cylindrical part        in at least partially radially constrained configuration, such        that the chord-recruiting arms assume a rotation configuration        in which the chord-recruiting arms extend at least radially from        the ventricular end of the cylindrical part, and curve        circumferentially around the cylindrical part in a given        circumferential direction, and    -   the delivery device is configured to rotate at least the portion        of the valve frame, while the chord-recruiting arms are disposed        in the rotation configuration.

In some applications, subsequent to rotating at least the portion of thevalve frame,

-   -   the delivery device is configured to release the atrial part and        the cylindrical part of the valve frame, to thereby cause the        native atrio-ventricular valve to be held (a) radially inwardly        toward the valve frame, and (b) twisted around the valve frame,    -   by causing at least a portion of the native atrio-ventricular        valve to become trapped within the valve frame.

In some applications, when the atrial part and the cylindrical part ofthe valve frame have been released by the delivery device, thechord-recruiting arms are configured to define pockets, and the pocketsdefined by the chord-recruiting arms are configured to accommodate thetrapped portion of the native atrio-ventricular valve.

In some applications:

-   -   the delivery device is configured, initially, to rotate at least        the portion of the valve frame in an opposite circumferential        direction from the direction of circumferential curvature of the        chord-recruiting arms; and    -   the delivery device is configured, subsequently, to rotate at        least the portion of the valve frame in the direction of        circumferential curvature of the chord-recruiting arms, such as        to cause the plurality of chord-recruiting arms to (a) pull the        native atrio-ventricular valve radially inward toward the valve        frame, and (b) twist the native atrio-ventricular valve around        the valve frame, by recruiting and deflecting at least the        portion of the chords.

In some applications, in the rotation configuration of thechord-recruiting arms:

-   -   an outer surface of each of the chord-recruiting arms has a        smooth, convex curvature that extends along substantially a full        length of the chord-recruiting arm, such that during the        rotation of at least the portion of the valve frame in the        opposite circumferential direction from the direction of        circumferential curvature of the chord-recruiting arms, chords        slide over the outer surface of the chord-recruiting arm without        be recruited or caught by the chord-recruiting arm; and    -   an inner surface of each of the chord-recruiting arms has a        concave curvature, such that during the rotation of at least the        portion of the valve frame in the direction of circumferential        curvature of the chord-recruiting arms, the chords are recruited        within a space defined by the concave curvature.

In some applications, the disc-shaped portion of the atrial partincludes struts that define cells, and at least some of the struts havean undulating pattern that are configured to provide the cells of theflange with flexibility, such that the disc-shaped portion is able toadapt its shape to conform with changes in a shape of tissue on theatrial side of the valve annulus.

In some applications, the cells of the disc-shaped portion are curvedcircumferentially, such that outer tips of the cells point in a givencircumferential direction.

In some applications, the chord-recruiting arms are configured to curvearound the cylindrical part circumferentially in an opposite directionof circumferential curvature from the given circumferential direction.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the apparatusincluding:

-   -   a valve frame configured to support the prosthetic valve within        the native atrio-ventricular valve, the valve frame including:        -   an atrial part including a disc-shaped portion configured to            be deployed on an atrial side of the valve annulus, and a            frustoconical portion;        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the ventricle; and        -   a plurality of protruding struts that are configured to            protrude from outside the cylindrical part, the            frustoconical portion of the atrial part being coupled to            the cylindrical part via the protruding struts.

In some applications, the frustoconical portion of the atrial part iscoupled to the cylindrical part, such that there is axial overlapbetween at least the frustoconical portion of the atrial part and thecylindrical part.

In some applications, the plurality of protruding struts protrude fromoutside the cylindrical part from an axial location along thecylindrical part that is in a lowest 70 percent of a height of thecylindrical part.

In some applications, the frustoconical portion of the atrial part isstitched to the protruding struts. In some applications, thefrustoconical portion of the atrial part is welded to the protrudingstruts. In some applications, the frustoconical portion of the atrialpart is glued to the protruding struts.

In some applications, by virtue of the frustoconical portion of theatrial part being coupled to the cylindrical part via the protrudingstruts, strain that is generated upon a region of the valve frame atwhich the frustoconical portion of the atrial part is coupled to thecylindrical part is reduced, relative to if the frustoconical portion ofthe atrial part were to be directly coupled to the cylindrical part.

In some applications, the valve frame further includes a plurality ofchord-recruiting arms configured to extend at least radially from theventricular end of the cylindrical part.

In some applications, the apparatus further includes a delivery deviceconfigured to:

-   -   deliver the valve frame to the native atrio-ventricular valve,    -   subsequently, deploy the plurality of chord-recruiting arms        among the chords of the native atrio-ventricular valve, and    -   subsequently, rotate at least a portion of the valve frame, such        as to cause the plurality of chord-recruiting arms to (a) pull        the native atrio-ventricular valve radially inward toward the        valve frame, and (b) twist the native atrio-ventricular valve        around the valve frame, by recruiting and deflecting at least a        portion of the chords.

In some applications, a tip of each of the chord-recruiting arms isrounded such as to guide chords around the tip of the chord-recruitingarm without damaging tissue.

In some applications, a tip of each of the chord-recruiting arms iscushioned such as to guide chords around the tip of the chord-recruitingarm without damaging tissue.

In some applications:

-   -   the delivery device is configured to deploy the plurality of        chord-recruiting arms among the chords of the native        atrio-ventricular valve, while maintaining the cylindrical part        in at least partially radially constrained configuration, such        that the chord-recruiting arms assume a rotation configuration        in which the chord-recruiting arms extend at least radially from        the ventricular end of the cylindrical part, and curve        circumferentially around the cylindrical part in a given        circumferential direction, and    -   the delivery device is configured to rotate at least the portion        of the valve frame, while the chord-recruiting arms are disposed        in the rotation configuration.

In some applications, subsequent to rotating at least the portion of thevalve frame,

-   -   the delivery device is configured to release the atrial part and        the cylindrical part of the valve frame, to thereby cause the        native atrio-ventricular valve to be held (a) radially inwardly        toward the valve frame, and (b) twisted around the valve frame,    -   by causing at least a portion of the native atrio-ventricular        valve to become trapped within the valve frame.

In some applications, when the atrial part and the cylindrical part ofthe valve frame have been released by the delivery device, thechord-recruiting arms are configured to define pockets, and the pocketsdefined by the chord-recruiting arms are configured to accommodate thetrapped portion of the native atrio-ventricular valve.

In some applications:

-   -   the delivery device is configured, initially, to rotate at least        the portion of the valve frame in an opposite circumferential        direction from the direction of circumferential curvature of the        chord-recruiting arms; and    -   the delivery device is configured, subsequently, to rotate at        least the portion of the valve frame in the direction of        circumferential curvature of the chord-recruiting arms, such as        to cause the plurality of chord-recruiting arms to (a) pull the        native atrio-ventricular valve radially inward toward the valve        frame, and (b) twist the native atrio-ventricular valve around        the valve frame, by recruiting and deflecting at least the        portion of the chords.

In some applications, in the rotation configuration of thechord-recruiting arms:

-   -   an outer surface of each of the chord-recruiting arms has a        smooth, convex curvature that extends along substantially a full        length of the chord-recruiting arm, such that during the        rotation of at least the portion of the valve frame in the        opposite circumferential direction from the direction of        circumferential curvature of the chord-recruiting arms, chords        slide over the outer surface of the chord-recruiting arm without        be recruited or caught by the chord-recruiting arm; and    -   an inner surface of each of the chord-recruiting arms has a        concave curvature, such that during the rotation of at least the        portion of the valve frame in the direction of circumferential        curvature of the chord-recruiting arms, the chords are recruited        within a space defined by the concave curvature.

In some applications, the disc-shaped portion of the atrial partincludes struts that define cells, and at least some of the struts havean undulating pattern that are configured to provide the cells of theflange with flexibility, such that the disc-shaped portion is able toadapt its shape to conform with changes in a shape of tissue on theatrial side of the valve annulus.

In some applications, the cells of the disc-shaped portion are curvedcircumferentially, such that outer tips of the cells point in a givencircumferential direction.

In some applications, the valve frame further includes chord-recruitingarms that are configured to curve around the cylindrical partcircumferentially in an opposite direction of circumferential curvaturefrom the given circumferential direction.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the apparatusincluding:

-   -   a valve frame configured to support the prosthetic valve within        the native atrio-ventricular valve, the valve frame including:        -   an atrial part including a disc-shaped portion configured to            be deployed on an atrial side of the valve annulus, and a            frustoconical portion;        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the ventricle,        -   the frustoconical portion of the atrial part being coupled            to the cylindrical part, such that there is axial overlap            between at least the frustoconical portion of the atrial            part and the cylindrical part.

In some applications, the valve frame further includes a plurality ofprotruding struts that are configured to protrude from outside thecylindrical part, the frustoconical portion of the atrial part beingcoupled to the cylindrical part via the protruding struts.

In some applications, the frustoconical portion of the atrial part isdirectly coupled to the cylindrical part. In some applications, thefrustoconical portion of the atrial part is coupled to the cylindricalpart via stitching. In some applications, the frustoconical portion ofthe atrial part is coupled to the cylindrical part via welding. In someapplications, the frustoconical portion of the atrial part is coupled tothe cylindrical part via gluing.

In some applications, the frustoconical portion of the atrial part iscoupled to the cylindrical part, such that the frustoconical portion ofthe atrial part extends from an axial location along the cylindricalpart that is in a lowest 90 percent of a height of the cylindrical part.In some applications, the frustoconical portion of the atrial part iscoupled to the cylindrical part, such that the frustoconical portion ofthe atrial part extends from an axial location along the cylindricalpart that is in a lowest 70 percent of the height of the cylindricalpart. In some applications, the frustoconical portion of the atrial partis coupled to the cylindrical part, such that the frustoconical portionof the atrial part extends from an axial location along the cylindricalpart that is in a lowest 50 percent of the height of the cylindricalpart.

In some applications, the valve frame further includes a plurality ofchord-recruiting arms configured to extend at least radially from theventricular end of the cylindrical part.

In some applications, the apparatus further includes a delivery deviceconfigured to:

-   -   deliver the valve frame to the native atrio-ventricular valve,    -   subsequently, deploy the plurality of chord-recruiting arms        among the chords of the native atrio-ventricular valve, and    -   subsequently, rotate at least a portion of the valve frame, such        as to cause the plurality of chord-recruiting arms to (a) pull        the native atrio-ventricular valve radially inward toward the        valve frame, and (b) twist the native atrio-ventricular valve        around the valve frame, by recruiting and deflecting at least a        portion of the chords.

In some applications, a tip of each of the chord-recruiting arms isrounded such as to guide chords around the tip of the chord-recruitingarm without damaging tissue. In some applications, a tip of each of thechord-recruiting arms is cushioned such as to guide chords around thetip of the chord-recruiting arm without damaging tissue.

In some applications:

-   -   the delivery device is configured to deploy the plurality of        chord-recruiting arms among the chords of the native        atrio-ventricular valve while maintaining the cylindrical part        in at least partially radially constrained configuration, such        that the chord-recruiting arms assume a rotation configuration        in which the chord-recruiting arms extend at least radially from        the ventricular end of the cylindrical part, and curve        circumferentially around the cylindrical part in a given        circumferential direction, and    -   the delivery device is configured to rotate at least the portion        of the valve frame, while the chord-recruiting arms are disposed        in the rotation configuration.

In some applications, subsequent to rotating at least the portion of thevalve frame,

-   -   the delivery device is configured to release the atrial part and        the cylindrical part of the valve frame, to thereby cause the        native atrio-ventricular valve to be held (a) radially inwardly        toward the valve frame, and (b) twisted around the valve frame,    -   by causing at least a portion of the native atrio-ventricular        valve to become trapped within the valve frame.

In some applications, when the atrial part and the cylindrical part ofthe valve frame have been released by the delivery device, thechord-recruiting arms are configured to define pockets, and the pocketsdefined by the chord-recruiting arms are configured to accommodate thetrapped portion of the native atrio-ventricular valve.

In some applications:

-   -   the delivery device is configured, initially, to rotate at least        the portion of the valve frame in an opposite circumferential        direction from the direction of circumferential curvature of the        chord-recruiting arms; and    -   the delivery device is configured, subsequently, to rotate at        least the portion of the valve frame in the direction of        circumferential curvature of the chord-recruiting arms, such as        to cause the plurality of chord-recruiting arms to (a) pull the        native atrio-ventricular valve radially inward toward the valve        frame, and (b) twist the native atrio-ventricular valve around        the valve frame, by recruiting and deflecting at least the        portion of the chords.

In some applications, in the rotation configuration of thechord-recruiting arms:

-   -   an outer surface of each of the chord-recruiting arms has a        smooth, convex curvature that extends along substantially a full        length of the chord-recruiting arm, such that during the        rotation of at least the portion of the valve frame in the        opposite circumferential direction from the direction of        circumferential curvature of the chord-recruiting arms, chords        slide over the outer surface of the chord-recruiting arm without        be recruited or caught by the chord-recruiting arm; and    -   an inner surface of each of the chord-recruiting arms has a        concave curvature, such that during the rotation of at least the        portion of the valve frame in the direction of circumferential        curvature of the chord-recruiting arms, the chords are recruited        within a space defined by the concave curvature.

In some applications, the disc-shaped portion of the atrial partincludes struts that define cells, and at least some of the struts havean undulating pattern that are configured to provide the cells of theflange with flexibility, such that the disc-shaped portion is able toadapt its shape to conform with changes in a shape of tissue on theatrial side of the valve annulus.

In some applications, the cells of the disc-shaped portion are curvedcircumferentially, such that outer tips of the cells point in a givencircumferential direction.

In some applications, the valve frame further includes chord-recruitingarms that are configured to curve around the cylindrical partcircumferentially in an opposite direction of circumferential curvaturefrom the given circumferential direction.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the apparatusincluding:

-   -   a valve frame configured to support the prosthetic valve within        the native atrio-ventricular valve, the valve frame including:        -   an atrial part including a flange configured to be deployed            on an atrial side of the valve annulus, and a frustoconical            portion;        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the ventricle,        -   the flange includes struts that define cells, and at least            some of the struts have an undulating pattern that are            configured to provide the cells of the flange with            flexibility, such that the flange is able to adapt its shape            to conform with changes in a shape of tissue on the atrial            side of the valve annulus.

In some applications, the cells of the flange are curvedcircumferentially, such that outer tips of the cells point in a givencircumferential direction.

In some applications, the valve frame further includes a plurality ofchord-recruiting arms that are configured to extend radially from theventricular end of the cylindrical part, and that are configured tocurve around the cylindrical part circumferentially in an oppositedirection of circumferential curvature from the given circumferentialdirection.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the apparatusincluding:

-   -   a valve frame configured to support the prosthetic valve within        the native atrio-ventricular valve, the valve frame including:        -   an atrial part including a disc-shaped portion configured to            be deployed on an atrial side of the valve annulus;        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the ventricle;        -   a plurality of chord-recruiting arms configured to extend at            least radially from the ventricular end of the cylindrical            part, the plurality of chord-recruiting arms being            configured:        -   to be deployed among the chords of the native            atrio-ventricular valve, while the cylindrical part is            maintained in at least partially radially constrained            configuration, such that the chord-recruiting arms assume a            rotation configuration in which the chord-recruiting arms            extend at least radially from the ventricular end of the            cylindrical part, and curve circumferentially around the            cylindrical part in a given circumferential direction, and            in the rotation configuration of the chord-recruiting arms:            -   an outer surface of each of the chord-recruiting arms                has a smooth, convex curvature that extends along                substantially a full length of the chord-recruiting arm,                such that during rotation of at least the portion of the                valve frame in the opposite circumferential direction                from the direction of circumferential curvature of the                chord-recruiting arms, chords slide over the outer                surface of the chord-recruiting arm without be recruited                or caught by the chord-recruiting arm; and            -   an inner surface of each of the chord-recruiting arms                has a concave curvature, such that during rotation of at                least the portion of the valve frame in the direction of                circumferential curvature of the chord-recruiting arms,                the chords are recruited within a space defined by the                concave curvature.

In some applications, the outer surface of each of the chord-recruitingarms is covered with a low-friction fabric, such as to allow movement ofthe outer surface with respect to the chords without damaging tissue. Insome applications, the inner surface of each of the chord-recruitingarms is covered with a low-friction fabric, such as to allow movement ofthe inner surface with respect to the chords without damaging tissue. Insome applications, a tip of each of the chord-recruiting arms is roundedsuch as to guide chords around the tip of the chord-recruiting armwithout damaging tissue. In some applications, a tip of each of thechord-recruiting arms is cushioned such as to guide chords around thetip of the chord-recruiting arm without damaging tissue.

In some applications, the apparatus further includes a delivery deviceconfigured to:

-   -   deliver the valve frame to the native atrio-ventricular valve,    -   subsequently, deploy the plurality of chord-recruiting arms        among the chords of the native atrio-ventricular valve, while        maintaining the cylindrical part in at least partially radially        constrained configuration, such that the chord-recruiting arms        assume the rotation configuration, and    -   while the chord-recruiting arms are disposed in the rotation        configuration:        -   initially rotate at least a portion of the valve frame in an            opposite circumferential direction from the direction of            circumferential curvature of the chord-recruiting arms; and        -   subsequently, rotate at least the portion of the valve frame            in the direction of circumferential curvature of the            chord-recruiting arms, such as to cause the plurality of            chord-recruiting arms to (a) pull the native            atrio-ventricular valve radially inward toward the valve            frame, and (b) twist the native atrio-ventricular valve            around the valve frame, by recruiting and deflecting at            least the portion of the chords.

In some applications, subsequent to rotating at least the portion of thevalve frame, the delivery device is configured to release the atrialpart and the cylindrical part of the valve frame, to thereby cause thenative atrio-ventricular valve to held (a) radially inwardly toward thevalve frame and (b) twisted around the valve frame, by causing at leasta portion of the native atrio-ventricular valve to become trapped withinthe valve frame.

In some applications, when the atrial part and the cylindrical part ofthe valve frame have been released by the delivery device, thechord-recruiting arms are configured to define pockets, and the pocketsdefined by the chord-recruiting arms are configured to accommodate thetrapped portion of the native atrio-ventricular valve.

There is further provided, in accordance with some applications of thepresent invention, a method for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the methodincluding:

-   -   deploying a valve frame within the native atrio-ventricular        valve, by:        -   deploying an atrial part of the valve frame at least            partially within the subject's atrium, the atrial part            including a disc-shaped portion configured to be deployed on            an atrial side of the valve annulus, and a frustoconical            portion;        -   deploying a cylindrical part of the valve frame such that a            ventricular end of the cylindrical part is disposed within            the subject's ventricle, the prosthetic valve leaflets being            coupled to the cylindrical part,        -   a plurality of protruding struts protruding from outside the            cylindrical part, the frustoconical portion of the atrial            part being coupled to the cylindrical part via the            protruding struts.

There is further provided, in accordance with some applications of thepresent invention, a method for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the methodincluding:

-   -   deploying a valve frame within the native atrio-ventricular        valve, by:        -   deploying an atrial part of the valve frame at least            partially within the subject's atrium, the atrial part            including a disc-shaped portion configured to be deployed on            an atrial side of the valve annulus, and a frustoconical            portion;        -   deploying a cylindrical part of the valve frame such that a            ventricular end of the cylindrical part is disposed within            the subject's ventricle, the prosthetic valve leaflets being            coupled to the cylindrical part,    -   the frustoconical portion of the atrial part being coupled to        the cylindrical part, such that there is axial overlap between        at least the frustoconical portion of the atrial part and the        cylindrical part.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the apparatusincluding:

-   -   a valve frame configured to support the prosthetic valve within        the native atrio-ventricular valve, the valve frame including:        -   an atrial part including a disc-shaped portion configured to            be deployed on an atrial side of the valve annulus;        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the ventricle;        -   a plurality of chord-recruiting arms configured to extend at            least radially from the ventricular end of the cylindrical            part, the chord-recruiting arms being configured to deploy            among the chords of the native atrio-ventricular valve, and,            in response to the valve frame being rotated in a given            direction, to (a) pull the native atrio-ventricular valve            radially inward toward the valve frame, and (b) twist the            native atrio-ventricular valve around the valve frame, by            recruiting and deflecting at least a portion of the chords;            and        -   a plurality of anti-recoil elements extending from the            disc-shaped portion of the atrial part of the valve frame,            the anti-recoil elements being configured to prevent            rotation of the valve frame in the opposite direction to the            direction in which the valve frame was rotated.

There is further provided, in accordance with some applications of thepresent invention, a method for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the methodincluding:

-   -   placing a valve frame within the native atrio-ventricular valve,        the valve frame including:        -   an atrial part configured to be deployed on an atrial side            of the valve annulus,        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the subject's ventricle, and        -   a plurality of chord-recruiting arms configured to extend at            least radially from the ventricular end of the cylindrical            part;    -   causing the chord-recruiting arms to deploy among the chords of        the native atrio-ventricular valve;    -   rotating the valve frame in a given direction, such to (a) pull        the native atrio-ventricular valve radially inward toward the        valve frame, and (b) twist the native atrio-ventricular valve        around the valve frame, by recruiting and deflecting at least a        portion of the chords; and    -   deploying anti-recoil elements into tissue of the subject's        atrium, such as to prevent rotation of the valve frame in the        opposite direction to the direction in which the valve frame was        rotated.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with a delivery device and withprosthetic valve leaflets that are configured to be deployed within anative atrio-ventricular valve that is disposed between an atrium and aventricle of a heart of a mammalian subject, the nativeatrio-ventricular valve including a valve annulus, valve leaflets,chords, and papillary muscles, the apparatus including:

-   -   a valve frame configured to support the prosthetic valve within        the native atrio-ventricular valve, the valve frame including:        -   an atrial part including a disc-shaped portion configured to            be deployed on an atrial side of the valve annulus;        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the ventricle;        -   a plurality of chord-recruiting arms configured to extend at            least radially from the ventricular end of the cylindrical            part,    -   the valve frame including lever elements extending from the        chord-recruiting arms, the lever element being configured such        that when the chord-recruiting arms are deployed among the        chords of the native atrio-ventricular valve, and the lever        elements are held within the delivery device, the lever elements        cause the chord-recruiting arms to pivot radially outwards.

There is further provided, in accordance with some applications of thepresent invention, a method for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the methodincluding:

-   -   delivering a valve frame to the native atrio-ventricular valve        using a delivery device, the valve frame including:        -   an atrial part configured to be deployed on an atrial side            of the valve annulus,        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the subject's ventricle,        -   a plurality of chord-recruiting arms configured to extend at            least radially from the ventricular end of the cylindrical            part, and        -   lever elements extending from the chord-recruiting arms;    -   causing the chord-recruiting arms to deploy among the chords of        the native atrio-ventricular valve, at least partially by        holding lever elements within the delivery device, such as to        cause the chord-recruiting arms to pivot radially outwardly; and    -   rotating the valve frame in a given direction, such to (a) pull        the native atrio-ventricular valve radially inward toward the        valve frame, and (b) twist the native atrio-ventricular valve        around the valve frame, by recruiting and deflecting at least a        portion of the chords.

There is further provided, in accordance with some applications of thepresent invention, a method for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the methodincluding:

-   -   delivering a valve frame to the native atrio-ventricular valve        using a delivery device, the valve frame including:        -   an atrial part configured to be deployed on an atrial side            of the valve annulus,        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the subject's ventricle,        -   a plurality of chord-recruiting arms configured to extend at            least radially from the ventricular end of the cylindrical            part, the chord-recruiting arms being coupled to the            ventricular end of the cylindrical part via stitches;    -   causing the chord-recruiting arms to deploy among the chords of        the native atrio-ventricular valve, by releasing the        chord-recruiting arms from the delivery device, such that the        chord-recruiting arms extend radially outwardly by pivoting        about the stitches with respect to the cylindrical part; and    -   rotating the valve frame in a given direction, such to (a) pull        the native atrio-ventricular valve radially inward toward the        valve frame, and (b) twist the native atrio-ventricular valve        around the valve frame, by recruiting and deflecting at least a        portion of the chords.

There is further provided, in accordance with some applications of thepresent invention, a method for use with prosthetic valve leaflets thatare configured to be deployed within a native atrio-ventricular valvethat is disposed between an atrium and a ventricle of a heart of amammalian subject, the native atrio-ventricular valve including a valveannulus, valve leaflets, chords, and papillary muscles, the methodincluding:

-   -   delivering a valve frame to the native atrio-ventricular valve        using a delivery device, the valve frame including:        -   an atrial part configured to be deployed on an atrial side            of the valve annulus,        -   a cylindrical part to which the prosthetic valve leaflets            are coupled, the cylindrical part configured to be deployed            such that a ventricular end of the cylindrical part is            disposed within the subject's ventricle,        -   a plurality of chord-recruiting arms configured to extend at            least radially from the ventricular end of the cylindrical            part, and configured to curve with respect to a longitudinal            axis of the valve frame in a given direction of            circumferential curvature;    -   causing the chord-recruiting arms to deploy among the chords of        the native atrio-ventricular valve, by releasing the        chord-recruiting arms from the delivery device;    -   subsequently, rotating the valve frame circumferentially in the        opposite direction to the direction of direction of        circumferential curvature of the chord-recruiting arms; and    -   further subsequently, rotating the valve frame circumferentially        in the direction of circumferential curvature of the        chord-recruiting arms such to (a) pull the native        atrio-ventricular valve radially inward toward the valve frame,        and (b) twist the native atrio-ventricular valve around the        valve frame, by recruiting and deflecting at least a portion of        the chords.

The present invention will be more fully understood from the followingdetailed description of applications thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, and 1C are schematic illustrations of respective views ofa valve frame that is configured to support a prosthetic valve within asubject's native atrio-ventricular valve, the figures showing the valveframe disposed in a non-radially-constrained configuration, inaccordance with some applications of the present invention;

FIG. 1D is a schematic illustration of the valve frame of FIGS. 1A, 1B,and 1C, in a non-radially-constrained configuration, showing valveleaflets and covering material attached to the valve frame, inaccordance with some applications of the present invention;

FIGS. 2A and 2B are schematic illustrations of the valve frame of FIGS.1A, 1B, and 1C fully disposed inside a delivery device (FIG. 2A), andwith chord-recruiting arms of the valve frame in “rotationconfigurations” (FIG. 2B), in accordance with some applications of thepresent invention;

FIGS. 3A and 3B are schematic illustrations of respective views of anatrial part of a valve frame, in accordance with some applications ofthe present invention;

FIGS. 4A and 4B are schematic illustrations of top views of atrial andcylindrical parts of a valve frame, in accordance with respectiveapplications of the present invention;

FIG. 5A is a schematic illustration of a side view of a cylindrical partof a valve frame in accordance with some applications of the presentinvention;

FIG. 5B is a schematic illustration of an atrial part of a valve framecoupled to a cylindrical part of the valve frame, in accordance withsome applications of the present invention;

FIG. 6A is a schematic illustration of chord-recruiting arms of a valveframe, in accordance with some applications of the present invention;

FIG. 6B is a schematic illustration of the chord-recruiting arms of FIG.6A coupled to a cylindrical part of the valve frame, in accordance withsome applications of the present invention;

FIGS. 7A and 7B are schematic illustrations of chord-recruiting arms ofa valve frame disposed in non-radially-constrained configurations (FIG.7A), and when lower ends of the arms are held within a delivery device,but the upper ends of the arms have been released from the deliverydevice (FIG. 7B), in accordance with some applications of the presentinvention;

FIGS. 8A, 8B, and 8C are schematic illustrations of respective views ofa valve frame in its non-radially-constrained configuration, inaccordance with some applications of the present invention;

FIGS. 9A and 9B are schematic illustrations of respective views of avalve-frame body of a valve frame, in accordance with some applicationsof the present invention;

FIGS. 10A and 10B are schematic illustrations of an atrial part of avalve frame, struts of the atrial part having an undulating pattern, inaccordance with some applications of the present invention; and

FIGS. 11A, 11B, 11C, 11D, 11E, and 11F are schematic illustrations ofrespective steps of the deployment of a prosthetic mitral valve via atransseptal approach, in accordance with some applications of thepresent invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to FIGS. 1A, 1B, and 1C, which are schematicillustrations of respective views of a valve frame 20, the figuresshowing the valve frame in its non-radially-constrained configuration,in accordance with some applications of the present invention. FIG. 1Ashows a side view of the valve frame, FIG. 1B shows a bottom view (i.e.,a view from a ventricular end of the valve frame), and FIG. 1C shows atop view (i.e., a view from an atrial end of the valve frame). Referenceis also made to FIG. 1D, which is a schematic illustration of valveframe 20, with valve leaflets 23 coupled to the valve frame, inaccordance with some applications of the present invention.

Typically, the valve frame includes a valve-frame body 21. For someapplications, valve-frame body 21 includes a cylindrical part 22, aswell as an atrial part 26. Typically, the cylindrical part is configuredto support the prosthetic valve within the native atrio-ventricularvalve. For example, leaflets 23 of the prosthetic valve may be suturedto the cylindrical part, and/or may be otherwise coupled to thecylindrical part, e.g., as shown in FIG. 1D. Typically, atrial part 26is configured to be deployed at least partially within the subject'satrium. For some applications, atrial part 26 includes a disc-shapedportion 28 (also referred to herein as a flange) and a frustoconicalportion 30.

Typically, the disc-shaped portion of the atrial part is configured toseal the valve frame with respect to tissue on the atrial side of themitral annulus, and is further configured to prevent migration of thevalve frame into the left ventricle. The frustoconical portion typicallyextends from the disc-shaped portion of the atrial part to the outersurface of the cylindrical part. For some applications, the inclusion ofthe frustoconical portion between the disc-shaped portion and thecylindrical part (as opposed to directly coupling the disc-shapedportion to the cylindrical part) reduces a likelihood of regurgitationaround the outside of the cylindrical part.

For some applications, the cylindrical part and the atrial part areformed as separate pieces from one another and are coupled to eachother, for example, via stitching, gluing, welding, and/or anothermethod. Alternatively, the cylindrical part and the atrial part areportions of a single integrally-formed piece, e.g., as describedhereinbelow with reference to FIGS. 8A-C.

Typically, valve frame 20 is made of a shape-memory material (e.g., ashape-memory alloy, such as nitinol and/or copper-aluminum-nickel),which is covered on one or both sides with a covering material 32 (shownin FIG. 1D), e.g., a fabric and/or a polymer (such as expandedpolytetrafluoroethylene (ePTFE), or woven, knitted, mesh and/or braidedpolyester). Typically, the shape-memory material of cylindrical part 22and atrial part 26 is shaped into a stent-like structure that comprisesstruts and/or cells of the shape-memory material. The covering materialis typically coupled to the shape-memory material via stitches 34 (shownin FIG. 1D). It is noted that FIGS. 1A-C (as well as FIGS. 3A-10B) showvalve frame 20 in the absence of valve leaflets 23 and covering material32 for illustrative purposes. However, valve leaflets 23, and coveringmaterial 32 may be observed in FIG. 1D.

For some applications, a plurality of chord-recruiting arms 24 (e.g.,more than two and/or fewer than twelve arms) extend from a portion ofvalve-frame body 21 that is configured to be placed within the subject'sventricle. For example, four chord-recruiting arms or sixchord-recruiting arms may extend from the valve-frame body. For someapplications, a single chord-recruiting arm 24 extends from a portion ofvalve-frame body 21 that is configured to be placed within the subject'sventricle. Typically, the chord-recruiting arms extend from cylindricalpart 22 of valve-frame body 21. Further typically, the chord-recruitingarms extend from a ventricular end of the cylindrical part (i.e., theend of the valve frame body that is configured to be placed within theventricle). Typically, in a non-radially constrained configuration ofthe valve frame (which the valve frame typically assumes when neitherthe valve frame body nor the chord-recruiting arms are constrained bythe delivery device), the arms extend radially from the valve-framebody, in addition to extending axially from the ventricular end of thevalve-frame body toward an atrial end of the valve-frame body (i.e., theend of the valve frame body that is configured to be placed within theatrium). Further typically, the arms curve around outside of thevalve-frame body in a given circumferential direction of curvature.

As noted in the Summary section, descriptions herein of the armsextending from the valve-frame body in a given direction should not beinterpreted as excluding additional directions in which the arms areoriented. Rather, the arms being described (or claimed) as extendingradially from the valve-frame body should be interpreted as meaning thatthe orientation of the arms with respect to the valve-frame bodyincludes a radial component. It is typically the case that, in additionto extending radially from the valve-frame body, the arms curvecircumferentially, and in some cases the orientation of the armsincludes an axial component. For some applications, at least along aportion of the arms, and at least in certain configurations of the arms,the arms are disposed tangentially with respect to the valve-frame body.

Typically, valve frame 20 with prosthetic valve leaflets 23 disposedtherein is delivered to the native atrio-ventricular valve, via adelivery device 40 (e.g., a delivery catheter, shown in FIG. 2), and thedelivery device is configured to maintain the valve frame and theprosthetic valve in radially-constrained configurations (i.e., “crimped”configurations) during the delivery. In accordance with respectiveapplications, the valve frame is delivered transapically (i.e., via theapex of the left ventricle), transseptally (i.e., via the vena cava, theright atrium, and the interatrial septum, as described in detail withreference to FIGS. 11A-F), and/or via a different delivery path. Forsome applications, when a distal end of the delivery device is disposedwithin the subject's ventricle, chord-recruiting arms 24 are deployedamong chords of the native atrio-ventricular valve. Typically, thechord-recruiting arms are deployed among chords of the nativeatrio-ventricular valve by releasing the chord-recruiting arms from thedelivery device, the chord-recruiting arms being shape set to extendfrom the valve-frame body, upon being released from the delivery device.For some applications, additional techniques are used in order to causethe chord-recruiting arms to become deployed among chords of the nativeatrio-ventricular valve by releasing the chord-recruiting arms from thedelivery device. For example, the valve frame may include leverelements, which are configured to cause the chord-recruiting arms toextend radially (e.g., as described hereinbelow with reference to FIGS.7A-B). Alternatively or additionally, the arms are coupled to thecylindrical part of the valve frame via stitches, the stitches acting ashinges, such that the arms pivot about the stitches with respect to thecylindrical part, as described hereinbelow. Typically, thechord-recruiting arms are released from the delivery device while thevalve-frame body is still maintained in an at least partiallyradially-constrained configuration by the delivery device. Typically,the valve frame is rotated while the chord-recruiting arms and thevalve-frame body are configured in the aforementioned configuration.Therefore, in the present application, the configuration of thechord-recruiting arms when the valve-frame body is still maintained inan at least partially radially-constrained configuration by the deliverydevice but the chord-recruiting arms have been released from thedelivery device is referred to as the “rotation configuration” of thechord-recruiting arms.

Reference is now made to FIGS. 2A and 2B. FIG. 2A is a schematicillustration of valve frame 20 fully disposed within a delivery device40, the delivery device typically including a proximal overtube 41 and anosecone 43, in accordance with some applications of the presentinvention. FIG. 2B is a schematic illustration of valve frame 20, whenthe chord-recruiting arms are disposed in their rotation configuration(i.e., when chord-recruiting arms 24 of the valve frame have beenreleased from a delivery device 40 while valve-frame body 21 of thevalve frame is still maintained in an at least partialradially-constrained configuration by the delivery device), inaccordance with some applications of the present invention. It is notedthat FIG. 2B shows the delivery device and the arms configured forinsertion from below the mitral valve (e.g., via transapical insertion).For some such applications, in their rotation configuration, the armsextend axially from the distal end of the delivery device in the distaldirection (i.e., the end of the delivery device that is further from theinsertion point of the delivery device into the subject's body), asshown. For some applications in which the delivery device is insertedfrom above the mitral valve (e.g., via transseptal insertion, asdescribed in detail hereinbelow with reference to FIGS. 11A-F), in theirrotation configuration, the arms extend axially from the distal end ofthe delivery device in the proximal direction (i.e., back toward theproximal end of the delivery device). For some applications, in theirrotation configuration, the chord-recruiting arms are configured toextend radially from valve frame and to curve circumferentially aroundthe valve frame, but not to extend axially in either the proximal or thedistal direction. Rather, for such applications, in their rotationconfiguration, the arms extend from the valve frame in the radialdirection with the arms disposed in a single plane along the axialdirection.

Subsequent to chord-recruiting arms 24 being deployed among chords ofthe native atrio-ventricular valve (and typically while valve-frame body21 is still maintained in the at least partially radially-constrainedconfiguration by the delivery device, as shown in FIG. 2), at least aportion of valve frame 20 is rotated, such as to cause chord-recruitingarms 24 to (a) pull the native atrio-ventricular valve radially inwardtoward the valve frame, and (b) twist the native atrio-ventricular valvearound the valve frame, by recruiting and deflecting at least a portionof the chords. For some applications, the valve frame is rotated duringventricular systole, when the native atrio-ventricular valve is closed,such that the rotation occurs when the chords are closest to the valveframe. Alternatively, the valve frame is rotated irrespective of thephase of the subject's cardiac cycle (i.e., without attempting tosynchronize the rotation with a particular phase of the subject'scardiac cycle).

Subsequent to the rotation of the valve-frame, cylindrical part 22 andatrial part 26 are typically allowed to radially expand, e.g., byreleasing the cylindrical part and the atrial part from the deliverydevice, such that the valve frame assumes its non-radially constrainedconfiguration. Typically, the valve frame is configured to thereby trapthe native valve leaflets in a partially closed and twistedconfiguration, to thereby at least partially seal a space between thenative atrio-ventricular valve and the prosthetic valve. For example,the cylindrical part may be configured to radially expand such as totrap the native valve leaflets between the cylindrical part and thechord-recruiting arms, and/or the atrial part may be configured toradially expand such as to trap the native valve leaflets between theatrial part and the chord-recruiting arms.

Typically, the chord-recruiting arms 24 are configured to curve in agiven circumferential direction with respect to the longitudinal axis ofthe valve frame, both when the arms are deployed among the chords (i.e.,when the arms are disposed in their rotation configuration), and whenthe cylindrical part 22 and atrial part 26 are allowed to radiallyexpand (i.e., the valve frame assumes its non-radially constrainedconfiguration), as described in further detail hereinbelow. For example,the arms may curve in a clockwise direction or in a counter-clockwisedirection with respect to the longitudinal axis of the valve frame.Typically, subsequent to chord-recruiting arms 24 being deployed amongchords of the native atrio-ventricular valve (and typically whilevalve-frame body 21 is still maintained in the at least partiallyradially-constrained configuration by the delivery device (i.e., whenthe arms are disposed in their rotation configuration), as shown in FIG.2), the valve frame is rotated in the same circumferential direction asthe direction of the circumferential curvature of the arms. For someapplications, prior to rotating the valve frame in this direction, thevalve frame is rotated in the opposite circumferential direction. Forexample, if the arms curve in the clockwise circumferential direction,then, subsequent to the arms being deployed among the chords, the valveframe may first be rotated in the counterclockwise direction and maysubsequently be rotated in the clockwise direction. For someapplications, rotating the valve frame in this manner facilitatesrecruitment of a greater portion of the chords than if the valve framewere to only be rotated in the direction of circumferential curvature ofthe arms.

As described in the above paragraph, for some applications, prior torotating the valve frame in the same circumferential direction as thedirection of the circumferential curvature of the arms, the valve frameis rotated in the opposite circumferential direction. For someapplications, the delivery device is configured such as to perform theinitial rotation of the valve frame through a given angle against thedirection of circumferential curvature of the arm, and to subsequentlyrotate the valve frame though a predetermined angle in the direction ofthe circumferential curvature of the arms. For some applications, in therotation configuration of the chord-recruiting arms, the outer surfacesof each of the arms has a smooth, convex curvature that extends alongsubstantially the full length of the arm, such that during the initialrotation (against the direction of circumferential curvature of the arm)the chords slide over the outer surfaces of the arm without be recruitedor caught by the arm. For some applications, by virtue of the arms beingshaped in this manner, the initial rotation of the valve frame causes arelatively large number of chords to be positioned such as to berecruited by each of the arms in the subsequent rotation step. Duringthe subsequent rotation of the valve frame (in the direction of thecircumferential curvature of the arms), the chords are recruited anddeflected by the arms. Typically, in the rotation configuration of thechord-recruiting arms, the inner surface of each of the arms has aconcave curvature and the chords are recruited within the space definedby the concave curvature, during the subsequent rotation by the valveframe.

Referring again to FIG. 1D, for some applications, covering material 32defines slits 42. Typically, when valve frame 20 is arranged in itsradially-constrained configuration inside the delivery device, cells ofthe valve frame become axially elongated. For some applications, slits42 are configured such as to allow the cells of the valve frame tobecome axially elongated without tearing the covering material, by theaxially-elongated cells extending through the slits. Typically, upon thevalve frame being released from the delivery device, and assuming itsnon-radially constrained configuration, the cells become reinserted intothe slits, such as to become covered by the covering material. It isnoted that, for illustrative purposes, in FIG. 1D, the tip of the cellsare shown as protruding from the slits even in thenon-radially-constrained configuration of the valve frame.

Reference is now made to FIGS. 3A and 3B, which are schematicillustrations of respective views of atrial part 26, in accordance withsome applications of the present invention. FIG. 3A shows athree-dimensional side view, and FIG. 3B shows a top view. As describedhereinabove, typically, atrial part 26 is configured to be deployed atleast partially within the subject's atrium. For some applications,atrial part 26 includes a disc-shaped portion 28 (also referred toherein as a flange) and a frustoconical portion 30. The disc-shapedportion is typically configured to be placed upon the native mitralvalve annulus, and the frustoconical portion extends from thedisc-shaped portion of the atrial part to cylindrical part 22.Typically, the disc-shaped portion of the atrial part is configured toseal the valve frame with respect to tissue on the atrial side of themitral annulus, and is further configured to prevent migration of thevalve frame into the left ventricle. For some applications, cells of theflange include spring portions 44. The spring portions are configured toprovide the cells with flexibility, such that the flange is able toadapt its shape to conform with changes in the shape of the atrialtissue that the flange contacts, during movement of the heart.Alternatively or additionally, the cells of the flange are provided withflexibility by virtue of struts of the cells themselves having anundulating pattern, as described in further detail hereinbelow withreference to FIGS. 10A-B. For some applications, the inclusion of thefrustoconical portion between the disc-shaped portion and thecylindrical part (as opposed to directly coupling the disc-shapedportion to the cylindrical portion) reduces a likelihood ofregurgitation around the outside of the cylindrical part. It is notedthat, in accordance with respective applications, the flange is disposedwithin a plane that is perpendicular to the longitudinal axis defined bythe cylindrical part, or is disposed at an angle to such a plane. Forexample, the flange may define an upwards angle or a downwards anglewith respect to a plane that is perpendicular to the longitudinal axisdefined by the cylindrical part, to best match the different anatomicalstructures surrounding the native atrioventricular valves, either in theatrium or ventricle.

For some applications, the frustoconical portion defines holes 50 at thebottom of at least some of the cells of the frustoconical portion.Typically the holes are configured to facilitate stitching of the atrialpart to the cylindrical part of the valve frame. For some applications,pairs 52 of struts 54 extend from respective cells of disc-shapedportion 28 of the atrial part. The pairs of struts converge to a point56. For some applications, pairs of struts are configured to piercetissue of the subject's heart (e.g., tissue of the valve annulus) atpoint 56. As described hereinabove, typically, the valve frame isrotated in order to recruit chords of the native valve, and,subsequently, the valve-frame body is allowed to radially expand. Insome cases, the valve frame has a tendency to undergo recoil and torotate in the opposite direction to the direction in which it wasrotated. Typically, by piercing tissue of the subject's heart at point56 (and then becoming embedded within the tissue), the pairs of strutsare configured to act as anti-recoil elements by preventing rotation ofthe valve frame in the opposite direction to the direction in which itwas rotated.

Reference is now made to FIGS. 4A and 4B, which are schematicillustrations of top views of atrial part 26 and cylindrical part 22, inaccordance with respective applications of the present invention. Asdescribed with reference to FIGS. 3A and 3B, for some applications,pairs 52 of struts 54 extend from respective cells of disc-shapedportion 28 of the atrial part. Typically, the pairs of struts areconfigured to act as anti-recoil elements by preventing rotation of thevalve frame in the opposite direction to the direction in which it wasrotated. For some applications, the pairs of struts additionallyfacilitate anchoring of the atrial part to the native tissue.

As shown in FIG. 4A, for some applications the pairs of struts arecurved with respect to the axis of the valve frame, in a circumferentialdirection. Typically, the curvature of the pairs of struts is configuredto facilitate the anti-recoil functionality, by the struts curving toface the direction in which the valve frame has a tendency to rotate.For example, in the example shown in FIG. 4A, the valve frame isconfigured to initially be rotated in a clockwise direction (when viewedfrom on top, as shown in FIG. 4A). In some cases, the valve frametherefore has a tendency to recoil and to rotate in the counterclockwisedirection. The curvature of the pairs of struts is such that as thevalve frame begins to rotate in the counterclockwise direction, points56 of pairs 52 of struts 54 pierce the tissue of the subject's heart(and become at least partially embedded within the tissue), therebyopposing further rotation of the valve frame.

Typically, each strut 54 of a given pair 52 is configured to extend froma strut of a respective side (i.e., a left-side or a right side) of acell of disc-shaped portion 28 of the atrial part. As shown in FIG. 4A,for some applications, each strut 54 of a given pair 52 is configured toextend from a strut of a respective side of an outer half of a cell ofdisc-shaped portion 28 of the atrial part. Alternatively, as shown inFIG. 4B, each strut 54 of a given pair 52 is configured to extend from astrut of a respective side (i.e., a left-side or a right side) of aninner half of a cell of disc-shaped portion 28 of the atrial part.

For some applications, in addition to being curved (as described withreference to FIG. 4A), pairs 52 of struts 54 are twisted with respect tothe cell from which they extend. For example, as shown in FIG. 4B, strut58 is connected to strut 60, which is on the inner left side of a cellof the disc-shaped portion 28 of the atrial part. Strut 62 is connectedto strut 64, which is on the inner right side of a cell of thedisc-shaped portion 28 of the atrial part. Struts 60 and 64 form ajunction 66 with each other. Strut 58 is connected to strut 60 at alocation that is closer to junction 66 than the location of theconnection between strut 62 with strut 64. This results in the pair 52of struts 58 and 62 being twisted with respect to the disc-shapedportion 28 of the atrial part. For some applications, the twistedness ofpairs 52 of struts is configured to facilitate the anti-recoilfunctionality of the pairs of struts, by the struts becoming moreembedded within tissue of the subject's heart (in response to the valveframe starting to undergo recoil) than if the struts were not to havethe twisted configuration. For some applications, valve frame 20 doesnot include anti-recoil elements, as described with reference to FIGS.4A-B.

Reference is now made to FIG. 5A, which is a schematic illustration of aside view of cylindrical part 22, in accordance with some applicationsof the present invention. Reference is also made to FIG. 5B, which is aschematic illustration of atrial part 26 coupled to cylindrical part 22,in accordance with some applications of the present invention. For someapplications, a plurality of struts 61 protrude from the outside ofcylindrical part 22. For some applications, the protrusion of the strutsfrom the outside of cylindrical part 22 is such that the orientation ofthe struts with respect to the cylindrical part has an a radial and anaxial component. For some applications, along at least a portion of thestruts, the struts are disposed tangentially with respect to thecylindrical part. Typically, the atrial part is coupled to thecylindrical part by the atrial part being coupled to protruding struts61. For example, as described hereinabove, frustoconical portion 30 ofatrial part 26 may define holes 50 at the bottom of at least some of thecells of the frustoconical portion. For some applications, protrudingstruts 61 also define holes 65, and the atrial part is coupled to thecylindrical part by stitching sutures through holes 50 defined by theatrial part and corresponding holes 65 defined by protruding struts 61of cylindrical part 22. Alternatively or additionally, the atrial partis coupled to the protruding struts via other means, e.g., via welding(such as laser welding), gluing, and/or a different method.

It is noted that, typically, during the crimping of the valve frame,there is a lot of strain that is placed on the junctions from whichprotruding struts 61 protrude from the cylindrical part, since thestruts pivot about these junctions. If the atrial part were to bedirectly coupled to the cylindrical part at these junctions, then thiswould mean that these points at which there is relatively large strainplaced on the valve frame are also points at which the two pieces arecoupled to each other, which would make the frame susceptible to fatigueat these points. By contrast, by virtue of the cylindrical partincluding protruding struts 61 and the atrial part being coupled to thecylindrical part via the struts, there is a separation between thepoints of high strain and the points at which atrial part is coupled tothe cylindrical part.

It is further noted that typically, the protruding struts protrude froman axial location along the cylindrical part that is in the lowest 90percent (e.g., the lowest 70 percent, or the lowest 50 percent) of theheight of the cylindrical part. Typically, the cylindrical part has aheight of at least 15 mm, in order to accommodate the coupling of thevalve leaflets to the cylindrical part. If the protruding struts were toprotrude from the top of the cylindrical part (or if the atrial partwere to be coupled directly to the cylindrical part at the top of thecylindrical part), then the entire height of the cylindrical part wouldbe disposed below the atrial part. By contrast, since the protrudingstruts protrude from the lowest 90 percent (e.g., the lowest 70 percent,or the lowest 50 percent) of the height of the cylindrical part, thereis typically axial overlap between the atrial part and the cylindricalpart of the valve frame, along the height of the cylindrical part.Typically, this results in a smaller portion of the height of thecylindrical part protruding into the subject's ventricle, then if therewere to be no axial overlap between the atrial part and the cylindricalpart of the valve frame (which poses less restriction on the ventricle,by reducing the ventricular presence of the cylindrical part). In turn(when valve frame 20 is configured for placement within the subject'sleft ventricle), this typically reduces obstruction of the leftventricular outflow tract, relative to if a larger portion of the heightof the cylindrical part were to protrude into the subject's ventricle.In this context, it is noted that, as described hereinabove,chord-recruiting arms 24 are typically configured to (a) pull the nativeatrio-ventricular valve radially inward toward the valve frame, and (b)twist the native atrio-ventricular valve around the valve frame, byrecruiting and deflecting at least a portion of the chords of the nativeatrioventricular valve. Typically, the recruitment and deflection of thechords in this manner serves to prevent obstruction of the leftventricular outflow tract by portions of the native mitral valveapparatus.

For some applications (not shown), the atrial part is coupled directlyto the cylindrical part (i.e., not via the protruding struts). Forexample, the atrial part may be coupled directly to cells and/or to celljunctions of the cylindrical part. For some applications, the atrialpart is coupled directly to the cylindrical part using sutures. For somesuch applications, the sutures act as hinges, such that the atrial partis able to move relative to the cylindrical part. Alternatively, theatrial part is coupled directly to the cylindrical part using adifferent method, such as welding, gluing, or a different method.Typically, in such cases, the coupling is such that there is axialoverlap between the atrial part and the cylindrical part of the valveframe, along the height of the cylindrical part, as described above.That is to say that, typically, the frustoconical portion of the atrialpart is coupled to the cylindrical part, such that the frustoconicalportion of the atrial part extends from an axial location along thecylindrical part that is in the lowest 90 percent (e.g., the lowest 70percent, or the lowest 50 percent) of a height of the cylindrical part.

Reference is now made to FIG. 6A, which is a schematic illustration ofchord-recruiting arms 24 of valve frame 20, in accordance with someapplications of the present invention. Reference is also made to FIG.6B, which is a schematic illustration of the chord-recruiting armscoupled to cylindrical part 22 of the valve frame. As describedhereinabove, for some applications, a plurality of chord-recruiting arms24 (e.g., more than two and/or fewer than twelve arms) extend from aportion of valve-frame body 21 that is configured to be placed withinthe subject's ventricle. For example, four chord-recruiting arms or sixchord-recruiting arms may extend from the valve-frame body. For someapplications, a single chord-recruiting arm 24 extends from a portion ofvalve-frame body 21 that is configured to be placed within the subject'sventricle. Typically, the chord-recruiting arms extend from cylindricalpart 22 of valve-frame body 21, as shown in FIG. 6B.

For some applications, each of chord-recruiting arms 24 is defined by apair 70 of struts 72, which extend from respective junctions of theventricular end of cylindrical part 22. Typically, the struts curve suchas to meet each other and form a junction at a tip 74 of the arm. Forsome applications, all of the chord-recruiting arms are cut from asingle piece 76 of a shape memory material (e.g., a shape-memory alloy,such as nitinol and/or copper-aluminum-nickel). The piece ofshape-memory material that defines the arms is typically coupled to thecylindrical part of the valve frame, as described in further detailhereinbelow. Typically, the arms are covered in covering material 32(shown in FIG. 2), e.g., a fabric and/or a polymer (such as expandedpolytetrafluoroethylene (ePTFE) and/or polyester).

Typically, chord-recruiting arms 24 of the valve frame are configured tobe released from delivery device 40 while valve-frame body 21 of thevalve frame is still maintained in an at least partialradially-constrained configuration by the delivery device, as describedhereinabove with reference to FIG. 2. In this first configuration of thechord-recruiting arms (referred to herein as the rotation configurationof the chord-recruiting arms), the arms are configured to becomedeployed among chords of the native atrioventricular valve, and are thenconfigured to (a) pull the native atrio-ventricular valve radiallyinward toward the valve frame, and (b) twist the nativeatrio-ventricular valve around the valve frame, by recruiting anddeflecting at least a portion of the chords. Subsequently, the valveframe body is allowed to assume its non-radially-constrainedconfiguration, by releasing the valve-frame body from the deliverydevice. Typically, the assumption of the non-radially-constrainedconfiguration by the valve-frame body causes the configuration of thechord-recruiting arms to change from their first configuration (i.e.,their rotation configuration) to a second configuration that isdifferent from the first configuration. In this second configuration,chord-recruiting arms 24 are configured to cause the chords and/or thenative valve leaflets to become trapped between the arms and portions ofthe valve-frame body. Typically, the second configuration of the armsensures robust anchoring between the trapped chords and/or the nativevalve leaflets with respect to the valve frame body and the prostheticvalve leaflets.

Typically, a first one of struts 72 of pair 70 of struts that comprise achord-recruiting arm is longer than a second strut of the pair. The pairof struts is configured such that, when the bases of the struts are heldtogether (when the arms are in their rotation configuration), the armsare relatively long and thin, such that the arms deploy among arelatively large number of chords, and subsequently, recruit and deflecta relatively large number of chords. For some applications, in thisconfiguration, each of the arms has a length of more than 10 mm (e.g.more than 20 mm, or more than 25 mm), measured along the axis of thearm. Typically, the arms are configured such that, when the arms are inthe rotation configuration, (a) the arms extend radially from thevalve-frame body, (b) the arms extend axially from a ventricular end ofthe valve-frame body (i.e., the end of the valve frame body that isconfigured to be placed within the ventricle) toward an atrial end ofthe valve-frame body (i.e., the end of the valve frame body that isconfigured to be placed within the atrium), and (c) the arms curvearound outside of the cylindrical part in a given direction ofcircumferential curvature. As described hereinabove, for someapplications, in their rotation configuration, the chord-recruiting armsare configured to extend radially from valve frame and to curvecircumferentially around the valve frame, but not to extend axially ineither the proximal or the distal direction. Rather, for suchapplications, in their rotation configuration, the arms extend from thevalve frame in the radial direction with the arms disposed in a singleplane along the axial direction.

In addition, as described hereinabove, for some applications, in therotation configuration of the chord-recruiting arms, the outer surfacesof each of the arms has a smooth, convex curvature that extends alongsubstantially the full length of the arm, such that during an initialrotation of the valve frame (against the direction of circumferentialcurvature of the arm) the chords slide over the outer surfaces of thearm without being recruited or caught by the arm, and without beingdamaged by the arms. For some applications, by virtue of the arms beingshaped in this manner, the initial rotation of the valve frame causes arelatively large number of chords to be positioned such as to berecruited by each of the arms in the subsequent rotation step. Duringthe subsequent rotation of the valve frame (in the direction of thecircumferential curvature of the arms), the chords are recruited anddeflected by the arms. Typically, in the rotation configuration of thechord-recruiting arms, the inner surface of the arm has a concavecurvature and the chords are recruited within the space defined by theconcave curvature, during the subsequent rotation by the valve frame.

Typically, the arms are configured such that in the second configurationof the arms (i.e., in the non-radially-constrained configuration of thevalve frame) the arms become shorter and (at least at the bases of thearms) the arms become wider, due the bases of the struts separating fromeach other. Typically, the arms define the three above-mentionedcurvatures in the second configuration. That is to say that, when thearms assume the second configuration, (a) the arms extend radially fromthe valve-frame body, (b) the arms extend axially from a ventricular endof the valve-frame body (i.e., the end of the valve frame body that isconfigured to be placed within the ventricle) toward an atrial end ofthe valve-frame body (i.e., the end of the valve frame body that isconfigured to be placed within the atrium), and (c) the arms curvearound outside of the cylindrical part in the given direction ofcircumferential curvature.

Typically, piece 76 of shape-memory material that defineschord-recruiting arms 24 is coupled to the cylindrical part of the valveframe, via stitching. For some applications, one of the struts of eachof the arms meets one of the struts of an adjacent arm at a junction 78.For some applications, the shape memory material defines a hole 79 atthe junction, through which a suture is inserted, and the suture is usedto create a stitch 82 that stitches the shape-memory material to thecylindrical part of the valve-frame body.

As described hereinabove with reference to FIG. 2, typically,chord-recruiting arms 24 of the valve frame are configured to bereleased from delivery device 40 while valve-frame body 21 of the valveframe is still maintained in an at least partial radially-constrainedconfiguration by the delivery device. For some applications, the armsare stitched to the cylindrical part at an axial location that isreleased from the delivery device, even at this stage. For some suchapplications, the stitches act as hinges, such that the arms pivot aboutthe stitches, with respect to the cylindrical part. For someapplications, this allows the arms to extend radially to a greaterdistance than if the stitches did not provide the aforementioned hingefunctionality. Alternatively or additionally, the valve frame includeslever elements, which are configured to cause the chord-recruiting armsto extend radially, as described hereinbelow with reference to FIGS.7A-B.

As indicated in FIGS. 6A and 6B, typically, tips 74 of chord-recruitingarms 24 are rounded. Alternatively or additionally, a thickened layer ofcovering material 32 (not shown in FIGS. 6A-B) is disposed over tips 74of the chord-recruiting arms, such that the tips of the arms arecushioned. For example, cushioning 75 is shown at tips 74 of thechord-recruiting arms in FIG. 2B. Typically, the roundness of the tipsand/or the cushioning of the tips is such that the tips of the arms areatraumatic. Further typically, this facilitates movement and rotation ofthe arms among the subject's chords and allows recruitment anddeflection of the chords by the arms, without causing damage to thechords or to other surrounding tissue. For some applications, theroundness and/or cushioning of the tips allows the chords to be guidedaround the tips during the rotation of the valve frame (e.g., thebidirectional rotation of the valve frame described hereinabove). Forsome applications, using a thickened layer of covering material 32 onthe tips of the arms (i.e., providing cushioning 75) facilitatessecurement of the trapped chords and native leaflets, after the releaseof the valve-frame body from the delivery device.

For some applications, covering material 32 (shown in FIG. 1D) isconfigured such as to provide different functionalities to respectiveregions of the valve frame. For example, areas of the valve frame thattypically come into contact with the chords (such as thechord-recruiting arms and the ventricular rim of the cylindricalportion) are typically covered with a low friction fabric (such as,PTFE) in order to provide low friction with respect to the chords and toallow the movement of these portions with respect to the chords withoutdamaging the tissue. Typically, one or both of the inner and outersurfaces of the chord-recruiting arms are covered with a low frictionfabric (such as, PTFE) in order to provide low friction with respect tothe chords and to allow the movement of these portions with respect tothe chords without damaging the tissue. Other areas of the valve framemay be covered with fabric that induces tissue ingrowth (e.g., a porousfabric), in order to cause these areas to become anchored to tissue ofthe subject. Such areas typically include portions of atrial part 26and/or cylindrical part 22 that contact the native atrioventricularvalve leaflets.

In general, the chord-recruiting arms typically define (a) aradially-constrained configuration when the arms are maintained incrimped configurations inside the delivery device, as well as (b) arotation configuration, when the arms are released from the deliverydevice, but the cylindrical part is maintained in an at least partiallyradially-constrained configuration by the delivery device, and (c) afully deployed configuration, when the entire valve-frame body,including the cylindrical part and the atrial part, is released from thedelivery device. In the rotation configuration, the arms are configuredto recruit and deflect the chords. For some applications, in therotation configuration, the arms are configured to pivot outwardly withrespect to the cylindrical part (e.g., by means of stitches 82, leverelements 80), such that the arms encompass a relatively large span andare thereby able to recruit a large number of chords during the rotationof the valve frame. Typically, there is a relatively large gap betweenthe tips of the arms and the valve frame body in this configuration, byvirtue of the arms pivoting outwardly with respect to the cylindricalpart. Further typically, in the fully deployed configuration (when theentire valve-frame body, including the cylindrical part and the atrialpart, is released from the delivery device), the chord-recruiting armsare configured to be disposed such as to define a relatively small gap G(defined hereinbelow with reference to FIG. 8C) between the tips of thearms and the outer surface of the valve-frame body (e.g., the outersurface of the cylindrical part), such that leaflets and or chords ofthe native atrioventricular valve are trapped between the arms and thevalve-frame body (e.g., the outer surface of the cylindrical part). Forsome applications, in the fully deployed configuration, thechord-recruiting arms are configured to define pockets P of space (shownin FIG. 8B) between themselves and the valve frame body (e.g., the outersurface of the cylindrical part), by virtue of the inner surfaces of thearms having a concave curvature. Typically, chords that are recruited bythe arms and/or tissue of the native valve leaflets are held withinthese pockets of space.

Reference is now made to FIGS. 7A-B, which are schematic illustrationsof chord-recruiting arms 24 disposed in non-radially-constrainedconfigurations (FIG. 7A), and when lower ends of the arms are heldwithin delivery device 40, but the upper ends of the arms have beenreleased from the delivery device (FIG. 7B), in accordance with someapplications of the present invention. As with many of the otherfigures, FIGS. 7A-B show chord-recruiting arms 24 in the absence ofcovering material 32, for illustrative purposes. For some applications,piece 76 of the shape-memory alloy that defines chord-recruiting arms24, defines lever elements 80. The lever elements are configured to beheld within delivery device 40, when the arms are disposed in theirrotational configuration (in which the arms are configured to deployamong the chords and then to recruit and deflect the chords). As shownin FIG. 7A, typically, the lever elements are configured to extend fromthe bases of arms 24 at an angle, when the valve frame is disposed inits non-radially-constrained configuration. By being held within thedelivery device, the lever elements are configured to cause the arms topivot radially outwards, as shown in FIG. 7B. This is indicated byarrows 86 and 88 in FIG. 7A. As shown, by moving (or holding) the leverelement in the direction of arrow 86, tip 74 of the arm is configured topivot radially outwardly in the direction of arrow 88.

Reference is now made to FIGS. 8A, 8B, and 8C, which are schematicillustrations of respective views of valve frame 20, the figures showingthe valve frame in its non-radially-constrained configuration, inaccordance with some applications of the present invention. Certainfeatures of valve frame 20 as shown in FIGS. 8A-C (and as the valveframe is also shown in FIGS. 9A-B) differ from the valve frame 20 asdescribed with reference to FIGS. 1A-7B, such features being describedhereinbelow. In all other aspects, valve frame 20 as shown in FIGS. 8A-C(and as the valve frame is also shown in FIGS. 9A-B) is generallysimilar to valve frame 20 as described with reference to FIGS. 1A-7B.Certain dimensions of valve frame 20 are described with respect to valveframe 20 as shown in FIGS. 8A-C and FIGS. 9A-B. Typically, generallysimilar dimensions are applicable to valve frame 20 as shown in FIGS.1A-7B, mutatis mutandis.

For some applications, cylindrical part 22 and atrial part 26 of valveframe 20 are made of a single integrally-formed piece of shape memorymaterial, as shown in FIGS. 8A-C.

Referring to FIGS. 8A-C, for some applications, valve frame 20 isconfigured such that in the absence of any forces acting on the valveframe (e.g., in the non-radially-constrained configuration of the valveframe), a height H1 of each of chord-recruiting arms 24 is more than 5mm (e.g., more than 7 mm), and/or less than 20 mm (e.g., less than 15mm), for example, 5-20 mm, or 7-15 mm For some applications, in thisconfiguration of the valve frame, a total height H2 of the valve frameis greater than 10 mm (e.g., greater than 15 mm), and/or less than 30 mm(e.g., less than 25 mm), e.g., 10-30 mm, or 15-25 mm

Referring to FIGS. 8A and 8B, for some applications, valve frame 20 isconfigured such that in the absence of any forces acting on the valveframe (e.g., in the non-radially-constrained configuration of the valveframe), a diameter D1 of cylindrical part 22 of valve-frame body 21 isgreater than 20 mm (e.g., greater than 25 mm), and/or less than 40 mm(e.g., less than 35 mm), e.g., 20-40 mm, or 25-35 mm For someapplications, in this configuration of the valve frame, a span S1defined by the chord-recruiting arms is greater than 22 mm (e.g.,greater than 26 mm), and/or less than 45 mm (e.g., less than 40 mm),e.g., 22-45 mm, or 26-40 mm. For some applications, in thisconfiguration of the valve frame, a gap G between the tips 74 of each ofchord-recruiting arms 24, and the outer surface of the valve-frame bodyis greater than 0.1 mm (e.g., greater than 0.5 mm), and/or less than 6mm (e.g., less than 5 mm), e.g., 0.1-6 mm, or 0.5-5 mm For someapplications, gap G is between the tips of the chord-recruiting arms,and the cylindrical part. Alternatively or additionally, gap G isbetween the tips of the chord-recruiting arms, and atrial part 26 (e.g.,frustoconical portion 30 of atrial part 26). Referring to FIG. 8B,typically, in the non-radially-constrained configuration of the valveframe, the chord-recruiting arms are configured such as to definepockets P of space between themselves and the valve frame body (e.g.,the outer surface of the cylindrical part), by virtue of the innersurfaces of the arms having a concave curvature. Typically, chords thatare recruited by the arms and/or tissue of the native valve leaflets areheld within these pockets of space. For some applications, the valveframe is shape set such that in the non-radially-constrainedconfiguration of the valve frame there is no gap between the tips 74 ofeach of chord-recruiting arms 24, and the outer surface of thevalve-frame body. For some applications, the arms are preloaded suchthat arms exert a force upon the outer surface of the valve frame body,for example, via shape-setting of the arms (such that, in suchapplications, if it were not for the frame blocking the tips of thearms, gap G would be less than zero).

Referring again to FIG. 2, for some applications, when chord-recruitingarms 24 of the valve frame have been released from a delivery device 40while valve-frame body 21 of the valve frame is still maintained in anat least partial radially-constrained configuration by the deliverydevice (i.e., when the chord-recruiting arms are disposed in theirrotation configuration), the chord-recruiting arms 24 are configured todefine a span S2 that is greater than 20 mm (e.g., greater than 25 mm),and/or less than 40 mm (e.g., less than 35 mm), e.g., 20-40 mm, or 25-35mm

Reference is now made to FIGS. 9A and 9B, which are schematicillustrations of respective views of valve-frame body 21 of valve frame20, in accordance with some applications of the present invention. Forillustrative purposes, FIGS. 9A-B show the valve-frame body in theabsence of chord-recruiting arms 24 of the valve frame.

As described hereinabove, typically, valve-frame body 21 is a stent-likestructure that comprises struts of the shape-memory material and that isshaped to define a generally-cylindrical shape. For some applications, aplurality of extensions 90 extend radially from the portion of thevalve-frame body that is configured to extend into the atrium.Typically, the extensions are configured to prevent migration of theprosthetic valve and/or the valve frame into the subject's ventricle.Alternatively or additionally, the extensions are configured such thatwhen the valve-frame body radially expands, the native valve leafletsbecome trapped between the extensions and the chord-recruiting arms. Forsome applications, the extensions are flexible (for example, theextensions may be shaped as springs, as shown), and are configured toconform with the shape of tissue of the mitral annulus on the atrialside of the mitral valve.

For some applications, valve frame 20 is configured such that in theabsence of any forces acting on the valve frame (e.g., in thenon-radially-constrained configuration of the valve frame), atrial part26 encompasses a radial distance D2 from the outer surface ofcylindrical part 22 that is greater than 5 mm (e.g., greater than 10mm), and/or less than 25 mm (e.g., less than 20 mm), e.g., 5-25 mm, or10-20 mm Referring again to FIG. 8B, for some applications, in thisconfiguration of the valve frame, atrial part 26 is configured to definea span S3 that is greater than 30 mm (e.g., greater than 35 mm), and/orless than 80 mm (e.g., less than 70 mm), e.g., 30-80 mm, or 35-70 mm

Reference is now made to FIGS. 10A and 10B, which are schematicillustrations of atrial part 26 of valve frame 20, struts 92 of whichhave an undulating pattern, in accordance with some applications of thepresent invention. FIG. 10 A shows only the atrial part of the valveframe, while FIG. 10B shows a top view of the atrial part coupled tocylindrical part 22 and chord-recruiting arms 24. For some applications,struts of disc-shaped portion (i.e., flange) 28 of the atrial part havean undulating pattern as shown. Typically, the undulating struts areconfigured to provide the cells of the flange with flexibility, suchthat the flange is able to adapt its shape to conform with changes inthe shape of tissue of the mitral annulus on the atrial side of themitral valve that the flange contacts. For some applications, theundulating struts are configured to provide the cells a betterdistribution of stress and strain when bending, relative to straightstruts. For some applications, the cells of the flange have acircumferential curvature, such that outer tips 94 of the cells point ina given circumferential direction. Typically, the circumferentialcurvature of the cells is in the opposite direction from the directionof circumferential curvature of the chord-recruiting arms. For someapplications, by defining this circumferential curvature, the cells ofthe flange are configured to act as anti-recoil elements, and to preventrotation of the valve frame in the opposite direction to the directionin which it was rotated.

Reference is now made to FIGS. 11A, 11B, 11C, 11D, 11E, and 11F, whichare schematic illustrations of respective steps of the delivery anddeployment of a prosthetic mitral valve, via a transseptal approach, inaccordance with some applications of the present invention. Typically,the prosthetic mitral valve includes valve frame body as describedhereinabove, with prosthetic valve leaflets 23 sutured to thecylindrical part, and/or otherwise coupled to cylindrical part 22 of thevalve frame, e.g., as shown in FIG. 1D. As described hereinabove, inaccordance with respective applications, the prosthetic mitral valve isdelivered transseptally (i.e., via the vena cava, the right atrium, andthe interatrial septum), transapically (i.e., via the apex of the leftventricle), and/or via a different delivery path. FIGS. 11A-F showssteps of delivery and deployment of a prosthetic mitral valve, via thetransseptal approach, by way of illustration and not limitation.

Typically, delivery device 40 (e.g., delivery catheter) is guided towardthe subject's native mitral valve 100 over a guidewire 102. As shown inFIG. 11A, the distal end of delivery device 40 is typically advancedinto the subject's left atrium 104, via the interatrial septum 106. Thedistal end of the delivery device is advanced toward the native mitralvalve, and is advanced through leaflets 108 of the native mitral valveand into left ventricle 110, as shown in FIG. 11B. When the distal endof the delivery device is disposed within the left ventricle,chord-recruiting arms 24 are allowed to at least partially radiallyexpand, and assume their rotation configurations, as shown in FIG. 11C.For some applications, the arms are allowed to assumenon-radially-constrained configurations by releasing the arms from beingradially constrained by the delivery device, e.g., by partiallyretracting proximal overtube 41, and/or by partially advancing distalnosecone 43. Typically, the chord-recruiting arms are shape set toextend radially from valve-frame body 21 and to curve circumferentiallyaround the valve-frame body (e.g., in the clockwise direction, asshown), upon assuming their rotation configurations. For someapplications, the chord-recruiting arms are further configured to extendaxially toward the subject's atrium. Typically, the chord-recruitingarms are configured to become deployed among chords 112 of the nativemitral valve upon being released from the delivery device.

As shown in FIG. 11D, subsequent to the chord-recruiting arms 24 beingdeployed among chords of the native mitral valve, at least a portion ofvalve frame 20 is rotated in the direction of arrow 114, such as tocause chord-recruiting arms 24 to (a) pull the native atrioventricularvalve radially inward toward the valve frame, and (b) twist the nativeatrioventricular valve around the valve frame, by recruiting anddeflecting at least a portion of the chords. Typically, thechord-recruiting arms 24 are configured to curve in a givencircumferential direction with respect to the longitudinal axis of thevalve frame. For example, the arms may curve in a clockwise direction orin a counter-clockwise direction with respect to the longitudinal axisof the valve frame. Typically, subsequent to chord-recruiting arms 24being deployed among chords of the native mitral valve, the valve frameis rotated in the same circumferential direction as the direction of thecircumferential curvature of the arms. In the example shown in FIG. 11D,the arms curve in the clockwise circumferential direction (as viewedfrom left atrium 104), and the valve frame is rotated in this direction.

As described hereinabove, for some applications, prior to rotating thevalve frame in the same circumferential direction as the direction ofthe circumferential curvature of the arms, the valve frame is rotated inthe opposite circumferential direction. For some applications, thedelivery device 40 is configured such as to automatically perform theinitial rotation of the valve frame through a given angle against thedirection of circumferential curvature of the arm, and to subsequentlyrotate the valve frame though a predetermined angle in the direction ofthe circumferential curvature of the arms. For some applications, in therotation configuration of the arms (shown in FIGS. 11C-D), the outersurfaces of each of the arms has a smooth, convex curvature that extendsalong substantially the full length of the arm, such that during theinitial rotation (against the direction of circumferential curvature ofthe arm) the chords slide over the outer surfaces of the arm without berecruited or caught by the arm. For some applications, by virtue of thearms being shaped in this manner, the initial rotation of the valveframe causes a relatively large number of chords to be positioned suchas to be recruited by each of the arms in the subsequent rotation step.During the subsequent rotation of the valve frame (in the direction ofthe circumferential curvature of the arms, e.g., the direction of arrow114 as shown in FIG. 11D), the chords are recruited and deflected by thearms. Typically, in the rotation configuration of the arms (shown inFIGS. 11C-D), the inner surface of the arm has a concave curvature andthe chords are recruited within the space defined by the concavecurvature, during the subsequent rotation by the valve frame.

Subsequent to chord-recruiting arms 24 having been released and valveframe 20 having been rotated, valve-frame body 21 (i.e., cylindricalpart 22 and atrial part 26 of the valve frame) is allowed to assume itsnon-radially-constrained configurations. For some applications, theatrial part is allowed to assume its non-radially-constrainedconfiguration by releasing the atrial part from the delivery device,e.g., by retracting proximal overtube 41. For some applications, thecylindrical part is allowed to assume its non-radially-constrainedconfiguration by releasing the cylindrical part from the deliverydevice, e.g., by advancing distal nosecone 43. FIG. 11E shows bothcylindrical part 22 and atrial part 26 in their non-radially-constrained(i.e., radially-expanded) configurations. Typically, by the valve-framebody assuming its non-radially-constrained configuration, thevalve-frame body is configured to trap the native valve leaflets 108 ina partially closed and twisted configuration, to thereby at leastpartially seal a space between the native mitral valve and theprosthetic valve. For example, the cylindrical part may be configured toradially expand such as to trap the native valve leaflets between thecylindrical part and the chord-recruiting arms, and/or the atrial partmay be configured to radially expand such as to trap the native valveleaflets between the atrial portion and the chord-recruiting arms. Forsome applications, the trapping of native valve leaflets 108 in apartially closed and twisted configuration is achieved by trapping thechords (which are attached to the leaflets) in twisted configurations.Subsequent to the above described steps being performed, delivery device40 is typically then retracted in its entirety from the subject's leftatrium, as indicated by arrow 120 in FIG. 11F.

The apparatus and methods described herein are typically performed withrespect to a subject's mitral valve and/or with respect to a subject'stricuspid valve. Although some embodiments of the apparatus and methodshave been described primarily in relation to a mitral valve, the scopeof the present invention includes applying any of the apparatus andmethods described hereinabove to the tricuspid valve, mutatis mutandis.

For some applications, apparatus and methods described herein areperformed in conjunction with apparatus and methods described in US2015/0173897 to Raanani, which is incorporated herein by reference.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

1. An apparatus for use with prosthetic valve leaflets that areconfigured to be deployed within a native atrio-ventricular valve thatis disposed between an atrium and a ventricle of a heart of a mammaliansubject, the native atrio-ventricular valve including a valve annulus,valve leaflets, chords, and papillary muscles, the apparatus comprising:a valve frame configured to support the prosthetic valve within thenative atrio-ventricular valve, the valve frame comprising: an atrialpart comprising a disc-shaped portion configured to be deployed on anatrial side of the valve annulus; a cylindrical part to which theprosthetic valve leaflets are coupled, the cylindrical part configuredto be deployed such that a ventricular end of the cylindrical part isdisposed within the ventricle; a plurality of chord-recruiting armsconfigured to extend at least radially from the ventricular end of thecylindrical part, the plurality of chord-recruiting arms beingconfigured: to be deployed among the chords of the nativeatrio-ventricular valve, while the cylindrical part is maintained in atleast partially radially constrained configuration, such that thechord-recruiting arms assume a rotation configuration in which thechord-recruiting arms extend at least radially from the ventricular endof the cylindrical part, and curve circumferentially around thecylindrical part in a given circumferential direction, wherein, in therotation configuration of the chord-recruiting arms: an outer surface ofeach of the chord-recruiting arms has a smooth, convex curvature thatextends along substantially a full length of the chord-recruiting arm,such that during rotation of at least a portion of the valve frame inthe opposite circumferential direction from the direction ofcircumferential curvature of the chord-recruiting arms, chords slideover the outer surface of the chord-recruiting arm without be recruitedor caught by the chord-recruiting arm; and an inner surface of each ofthe chord-recruiting arms has a concave curvature, such that duringrotation of at least the portion of the valve frame in the direction ofcircumferential curvature of the chord-recruiting arms, the chords arerecruited within a space defined by the concave curvature.
 2. Theapparatus according to claim 1, wherein the outer surface of each of thechord-recruiting arms is covered with a low-friction fabric, such as toallow movement of the outer surface with respect to the chords withoutdamaging tissue.
 3. The apparatus according to claim 1, wherein theinner surface of each of the chord-recruiting arms is covered with alow-friction fabric, such as to allow movement of the inner surface withrespect to the chords without damaging tissue.
 4. The apparatusaccording to claim 1, wherein a tip of each of the chord-recruiting armsis rounded such as to guide chords around the tip of thechord-recruiting arm without damaging tissue.
 5. The apparatus accordingto claim 1, wherein a tip of each of the chord-recruiting arms iscushioned such as to guide chords around the tip of the chord-recruitingarm without damaging tissue.
 6. The apparatus according to any one ofclaims 1, further comprising a delivery device configured to: deliverthe valve frame to the native atrio-ventricular valve, subsequently,deploy the plurality of chord-recruiting arms among the chords of thenative atrio-ventricular valve, while maintaining the cylindrical partin at least partially radially constrained configuration, such that thechord-recruiting arms assume the rotation configuration, and while thechord-recruiting arms are disposed in the rotation configuration:initially rotate at least a portion of the valve frame in an oppositecircumferential direction from the direction of circumferentialcurvature of the chord-recruiting arms; and subsequently, rotate atleast the portion of the valve frame in the direction of circumferentialcurvature of the chord-recruiting arms, such as to cause the pluralityof chord-recruiting arms to (a) pull the native atrio-ventricular valveradially inward toward the valve frame, and (b) twist the nativeatrio-ventricular valve around the valve frame, by recruiting anddeflecting at least the portion of the chords.
 7. The apparatusaccording to claim 6, wherein, subsequent to rotating at least theportion of the valve frame, the delivery device is configured to releasethe atrial part and the cylindrical part of the valve frame, to therebycause the native atrio-ventricular valve to held (a) radially inwardlytoward the valve frame and (b) twisted around the valve frame, bycausing at least a portion of the native atrio-ventricular valve tobecome trapped within the valve frame.
 8. The apparatus according toclaim 7, wherein, when the atrial part and the cylindrical part of thevalve frame have been released by the delivery device, thechord-recruiting arms are configured to define pockets, and wherein thepockets defined by the chord-recruiting arms are configured toaccommodate the trapped portion of the native atrio-ventricular valve.9. A method for use with prosthetic valve leaflets that are configuredto be deployed within a native atrio-ventricular valve that is disposedbetween an atrium and a ventricle of a heart of a mammalian subject, thenative atrio-ventricular valve including a valve annulus, valveleaflets, chords, and papillary muscles, the method comprising:delivering a valve frame to the native atrio-ventricular valve, thevalve frame including: an atrial part comprising a disc-shaped portionconfigured to be deployed on an atrial side of the valve annulus; acylindrical part to which the prosthetic valve leaflets are coupled, thecylindrical part configured to be deployed such that a ventricular endof the cylindrical part is disposed within the ventricle; a plurality ofchord-recruiting arms configured to extend at least radially from theventricular end of the cylindrical part; deploying the chord-recruitingarms among the chords of the native atrio-ventricular valve, while thecylindrical part is maintained in at least partially radiallyconstrained configuration, such that the chord-recruiting arms assume arotation configuration in which the chord-recruiting arms extend atleast radially from the ventricular end of the cylindrical part, andcurve circumferentially around the cylindrical part in a givencircumferential direction; rotating at least a portion of the valveframe in an opposite circumferential direction from the direction ofcircumferential curvature of the chord-recruiting arms, wherein, in therotation configuration of the chord-recruiting arms, an outer surface ofeach of the chord-recruiting arms has a smooth, convex curvature thatextends along substantially a full length of the chord-recruiting arm,such that during the rotation of at least the portion of the valve framein the opposite circumferential direction from the direction ofcircumferential curvature of the chord-recruiting arms, the chords slideover the outer surface of the chord-recruiting arm without be recruitedor caught by the chord-recruiting arm; and subsequently, rotating atleast the portion of the valve frame in the direction of circumferentialcurvature of the chord-recruiting arms, wherein, in the rotationconfiguration of the chord-recruiting arms, an inner surface of each ofthe chord-recruiting arms has a concave curvature, such that during therotation of at least the portion of the valve frame in the direction ofcircumferential curvature of the chord-recruiting arms, the chords arerecruited within a space defined by the concave curvature.
 10. Themethod according to claim 9, wherein the outer surface of each of thechord-recruiting arms is covered with a low-friction fabric, such as toallow movement of the outer surface with respect to the chords withoutdamaging tissue.
 11. The method according to claim 9, wherein the innersurface of each of the chord-recruiting arms is covered with alow-friction fabric, such as to allow movement of the inner surface withrespect to the chords without damaging tissue.
 12. The method accordingto claim 9, wherein a tip of each of the chord-recruiting arms isrounded such as to guide chords around the tip of the chord-recruitingarm without damaging tissue.
 13. The method according to claim 9,wherein a tip of each of the chord-recruiting arms is cushioned such asto guide chords around the tip of the chord-recruiting arm withoutdamaging tissue.
 14. The method according to claim 9, wherein rotatingat least the portion of the valve frame in the direction ofcircumferential curvature of the chord-recruiting arms comprises causingthe plurality of chord-recruiting arms to (a) pull the nativeatrio-ventricular valve radially inward toward the valve frame, and (b)twist the native atrio-ventricular valve around the valve frame, byrecruiting and deflecting at least the portion of the chords.
 15. Themethod according to claim 14, further comprising, subsequent to rotatingat least the portion of the valve frame in the direction ofcircumferential curvature of the chord-recruiting arms, releasing theatrial part and the cylindrical part of the valve frame, to therebycause the native atrio-ventricular valve to be held (a) radiallyinwardly toward the valve frame and (b) twisted around the valve frame,by causing at least a portion of the native atrio-ventricular valve tobecome trapped within the valve frame.
 16. The method according to claim14, wherein, releasing the atrial part and the cylindrical part of thevalve frame comprises causing the chord-recruiting arms to definepockets that accommodate the trapped portion of the nativeatrio-ventricular valve.
 17. An apparatus for use with prosthetic valveleaflets that are configured to be deployed within a nativeatrio-ventricular valve that is disposed between an atrium and aventricle of a heart of a mammalian subject, the nativeatrio-ventricular valve including a valve annulus, valve leaflets,chords, and papillary muscles, the apparatus comprising: a valve frameconfigured to support the prosthetic valve within the nativeatrio-ventricular valve, the valve frame comprising: an atrial partcomprising a flange configured to be deployed on an atrial side of thevalve annulus, and a frustoconical portion; a cylindrical part to whichthe prosthetic valve leaflets are coupled, the cylindrical partconfigured to be deployed such that a ventricular end of the cylindricalpart is disposed within the ventricle, wherein the flange comprisesstruts that define cells, and wherein at least some of the struts havean undulating pattern that are configured to provide the cells of theflange with flexibility, such that the flange is able to adapt its shapeto conform with changes in a shape of tissue on the atrial side of thevalve annulus.